Method and apparatus for information transmission in a radio communication system

ABSTRACT

A method of transmitting, by a transmitter, information in a wireless communication system, the method includes generating first and second symbols; generating first and second transmit vectors on the basis of an Alamouti code from the first and second symbols; and transmitting the first transmit vector through a first antenna and transmitting the second transmit vector through a second antenna. The first transmit vector consists of a first transmit symbol and a second transmit symbol. The second transmit vector consists of a third transmit symbol and a fourth transmit symbol. The first, second, third, and fourth transmit symbols are transmitted based on first and second resource indexes. The first symbol is a first modulation symbol for first information, and the second symbol is a second modulation symbol for second information.

This application is a Continuation of application Ser. No. 13/743,176filed Jan. 16, 2013, which is a Continuation of application Ser. No.13/058,395 filed on Feb. 10, 2011 (now U.S. Pat. No. 8,385,467), whichis a National Phase of PCT/KR2009/004479 filed on Aug. 11, 2009, whichclaims the benefit under 35 U.S.C. 119(e) of U.S. ProvisionalApplication Nos. 61/087,737; 61/114,479; 61/115,113; 61/116,298 and61/117,237 filed on Aug. 11, 2008; Nov. 14, 2008; Nov. 17, 2008; Nov.20, 2008 and Nov. 24, 2008 respectively, and claims priority under 35U.S.C. 119 (a) to Patent Application No. 10-2009-0062712 filed inRepublic of Korea on Jul. 9, 2009, all of which are hereby expresslyincorporated by reference into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to wireless communications, and moreparticularly, to a method and apparatus for information transmission ina radio communication system.

2. Related Art

In next generation multimedia radio communication systems, which havebeen actively studied in recent years, there is a demand for a systemcapable of processing and transmitting a variety of information (e.g.,video and radio data) at a higher data rate in addition to theearly-stage voice service. The radio communication system is designedfor the purpose of providing reliable communication to a plurality ofusers irrespective of their locations and mobility. However, a wirelesschannel has an abnormal characteristic such as a fading phenomenoncaused by a path loss, noise, and multipath, an inter-symbolinterference (ISI), a Doppler effect caused by mobility of a userequipment (UE), etc. Various techniques have been developed to overcomethe abnormal characteristic of the wireless channel and to increasereliability of radio communication.

A multiple input multiple output (MIMO) scheme is used as a techniquefor supporting a reliable high-speed data service. The MIMO scheme usesmultiple transmit antennas and multiple receive antennas to improve datatransmission/reception efficiency. Examples of the MIMO scheme includespatial multiplexing, transmit diversity, beamforming, etc. A MIMOchannel matrix depending on the number of receive antennas and thenumber of transmit antennas can be decomposed into a plurality ofindependent channels. Each independent channel is referred to as aspatial layer or a stream. The number of streams is referred to as arank.

There is an ongoing standardization effort for an international mobiletelecommunication-advanced (IMT-A) system aiming at the support of anInternal protocol (IP)-based multimedia seamless service by using ahigh-speed data transfer rate of 1 gigabits per second (Gbps) in adownlink and 500 megabits per second (Mbps) in an uplink in theinternational telecommunication union (ITU) as a next generation (i.e.,post generation) mobile communication system. A 3^(rd) generationpartnership project (3GPP) is considering a 3GPP long termevolution-advanced (LTE-A) system as a candidate technique for the IMT-Asystem. It is expected that the LTE-A system is developed to furthercomplete an LTE system while maintaining backward compatibility with theLTE system. This is because the support of compatibility between theLTE-A system and the LTE system facilitates user convenience. Inaddition, the compatibility between the two systems is also advantageousfrom the perspective of service providers since the existing equipmentcan be reused.

A typical radio communication system is a single-carrier systemsupporting one carrier. Since a data transfer rate is in proportion to atransmission bandwidth, the transmission bandwidth needs to increase tosupport a high-speed data transfer rate. However, except for some areasof the world, it is difficult to allocate frequencies of widebandwidths. For the effective use of fragmented small bands, a spectrumaggregation (or bandwidth aggregation or a carrier aggregation)technique is being developed. The spectrum aggregation technique is atechnique for obtaining the same effect as when a band of a logicallywide bandwidth is used by aggregating a plurality of physicallynon-contiguous bands in a frequency domain. By using the spectrumaggregation technique, multiple carriers can be supported in the radiocommunication system. The radio communication system supporting themultiple carriers is referred to as a multiple carrier system. Thecarrier may also be referred to as other terms, such as, a radiofrequency (RF), a component carrier, etc.

Meanwhile, a variety of uplink control information is transmittedthrough an uplink control channel. Examples of the uplink controlinformation include an acknowledgement (ACK)/not-acknowledgement (NACK)used to perform hybrid automatic repeat request (HARQ), a channelquality indicator (CQI) for indicating a downlink channel state, ascheduling request (SR) for requesting radio resource allocation foruplink transmission, etc.

A plurality of user equipments (UEs) in a cell can transmit uplinkinformation simultaneously to a base station (BS). The BS needs to beable to identify each UE's uplink information simultaneouslytransmitted. When the uplink information of each UE is transmitted byusing a different frequency, the BS can identify the information.Frequency division multiplexing (FDM) is a multiplexing scheme in whicha plurality of UEs are multiplexed by using different frequencies.However, the plurality of UEs in the cell may transmit the uplinkinformation to the BS by using the same time-frequency resource. Inorder to identify each UE's uplink information transmitted using thesame time-frequency resource, an orthogonal sequence may be used by eachUE in uplink information transmission. Alternatively, a sequence havinga low correlation may be used. As such, a multiplexing scheme in whichthe plurality of UEs are multiplexed by using different sequences isreferred to as code division multiplexing (CDM). That is, uplinkinformation of the plurality of UEs can be transmitted by beingmultiplexed using the CDM and/or the FDM. However, when the CDM-basedinformation transmission method is combined with a multiple-inputmultiple-output (MIMO) technique, there may be a problem in thatorthogonality is not maintained. When the orthogonality is notmaintained, it becomes more difficult for the BS to identify informationof each UE than a case where the orthogonality is maintained. As aresult, reliability of radio communication may deteriorate, and overallsystem capability may become worse.

Accordingly, there is a need for a method and apparatus for effectiveinformation transmission by combining the MIMO scheme with the CDMand/or the FDM.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for informationtransmission in a radio communication system.

In an aspect, an information transmission method performed by atransmitter in a radio communication system is provided. The informationtransmission method include generating first and second symbolscorresponding to information, generating first and second transmitvectors on the basis of an Alamouti code from the first and secondsymbols, and transmitting the first transmit vector through a firstantenna and transmitting the second transmit vector through a secondantenna, wherein the first transmit vector consists of a first transmitsymbol and a second transmit symbol, the first transmit symbol istransmitted based on a first resource index, and the second transmitsymbol is transmitted based on a second resource index, and wherein thesecond transmit vector consists of a third transmit symbol and a fourthtransmit symbol, the third transmit symbol is transmitted based on thefirst resource index, and the fourth transmit symbol is transmittedbased on the second resource index.

Preferably, the first transmit symbol may be generated based on thefirst symbol, the second transmit symbol may be generated based on thesecond symbol, the third transmit symbol may be obtained by appending anegative sign to a complex conjugate of the second transmit symbol, andthe fourth transmit symbol may be a complex conjugate of the firsttransmit symbol.

Preferably, the resource index may include a sequence index indicating asequence, and the sequence allows a transmit symbol to be spread to afrequency domain or a time domain, and the first resource index and thesecond resource index may include different sequence indices.

Preferably, the sequence index may indicate a cyclic shift amount, andthe sequence may be generated by cyclically shifting a base sequence bythe cyclic shift amount.

Preferably, the sequence index may be one sequence index selected from aset of sequence indices, and sequences indicated by the sequence indicesmay be orthogonal to each other.

Preferably, a resource index may include resource block informationindicating a resource block on which a transmit symbol is transmittedand a sequence index indicating a sequence, and the sequence may allowthe transmit symbol to be spread to a frequency domain and a timedomain, and the first resource index and the second resource index mayinclude different resource block information or different sequenceindices.

Preferably, a resource index may include a frequency-domain sequenceindex indicating a frequency-domain sequence and a time-domain sequenceindex indicating a time-domain sequence, the frequency-domain sequenceand the time-domain sequence may allow the transmit symbol to be spreadto a 2 dimensional domain of a time-frequency domain, and the firstresource index and the second resource index may include differentfrequency-domain sequence indices or different time-domain sequenceindices.

Preferably, a resource index may include resource block informationindicating a resource block on which a transmit symbol is transmitted, afrequency-domain sequence index indicating a frequency-domain sequence,and a time-domain sequence index indicating a time-domain sequence, thefrequency-domain sequence and the time-domain sequence may allow thetransmit symbol to be spread to a 2 dimensional domain of atime-frequency domain, and at least one of the resource blockinformation, the frequency-domain sequence index, and the time-domainsequence index included in each of the first resource index and thesecond resource index may be different.

The information transmission method may further include obtaining thefirst resource index and the second resource index.

Preferably, the first symbol may be a first modulation symbol for firstinformation, and the second symbol may be a second modulation symbol forsecond information.

Preferably, the first information and the second information may bedifferent control information.

In another aspect, an apparatus for radio communication including amodulator for generating a first symbol and a second symbol bymodulating an information bit stream, a space block coding (SBC)processor for generating a first transmit vector consisting of a firsttransmit symbol and a second transmit symbol and a second transmitsymbol consisting of a third transmit symbol and a fourth transmitsymbol on the basis of an Alamouti code from the first and secondsymbols, a first antenna for transmitting the first transmit vector, anda second antenna for transmitting the second transmit vector, whereinthe first transmit symbol is transmitted based on a first resourceindex, and the second transmit symbol is transmitted based on a secondresource index, and wherein the third transmit symbol is transmittedbased on the first resource index, and the fourth transmit symbol istransmitted based on the second resource index is provided.

According to the present invention, a method and apparatus for effectiveinformation transmission in a radio communication system are provided.Therefore, overall system performance can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a radio communication system.

FIG. 2 shows HARQ acknowledgement (ACK)/non-acknowledgement (NACK) andCQI transmission.

FIG. 3 shows UL transmission.

FIG. 4 shows a structure of a radio frame in 3^(rd) generationpartnership project (3GPP) long term evolution (LTE).

FIG. 5 shows an example of a resource grid for one UL slot in 3GPP LTE.

FIG. 6 shows an example of a DL subframe structure in 3GPP LTE.

FIG. 7 shows an example of a UL subframe structure in 3GPP LTE.

FIG. 8 shows an example of PUCCH format 1/1a/1b transmission when anormal CP is used.

FIG. 9 shows an example of PUCCH format 1/1a/1b transmission when anextended CP is used.

FIG. 10 shows an example of PUCCH format 2/2a/2b transmission when anormal CP is used.

FIG. 11 shows an example of PUCCH format 2/2a/2b transmission when anextended CP is used.

FIG. 12 is a flowchart showing an example of an information transmissionmethod.

FIG. 13 is a flowchart showing another example of an informationtransmission method.

FIG. 14 is a flowchart showing another example of an informationtransmission method.

FIG. 15 is a flowchart showing an example of an information processingmethod based on a resource index.

FIG. 16 is a flowchart showing another example of an informationprocessing method based on a resource index.

FIG. 17 is a flowchart showing an information transmission methodaccording to an embodiment of the present invention.

FIG. 18 is a block diagram showing a transmitter for implementing anembodiment of the present invention.

FIG. 19 is a flowchart showing an information transmission methodaccording to another embodiment of the present invention.

FIG. 20 is a flowchart showing an information transmission methodaccording to another embodiment of the present invention.

FIG. 21 shows an example of an information transmission method when a1st RB and a 2nd RB are identical to each other.

FIG. 22 shows an example of an information transmission method when a1st RB and a 2nd RB are different from each other.

FIG. 23 is a block diagram showing an apparatus for radio communication.

FIG. 24 is a block diagram showing an example of a BS.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Techniques described below can be used in various multiple accessschemes such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier frequencydivision multiple access (SC-FDMA), etc. The SC-FDMA is a scheme inwhich inverse fast Fourier transform (IFFT) is performed oncomplex-valued symbols subjected to discrete Fourier transform (DFT)spreading, and is also referred to as DFT spreading-orthogonal frequencydivision multiplexing (DFTS-OFDM). In addition, the techniques describedbelow can also be used in a multiple access scheme modified from theSC-FDMA, for example, clustered SC-FDMA, N×SC-FDMA, etc. The clusteredSC-FDMA is a scheme in which complex-valued symbols subjected to DFTspreading are divided into a plurality of sub-blocks and the pluralityof sub-blocks are distributed in a frequency domain and are mapped tosubcarriers. The clustered SC-FDMA is also referred to as clusteredDFTS-OFDM. The N×SC-FDMA is a scheme in which a code block is dividedinto a plurality of chunks and DFT and IFFT are performed on a chunkbasis. The N×SC-FDMA is also referred to as chunk specific DFTS-OFDM.

The CDMA can be implemented with a radio technology such as universalterrestrial radio access (UTRA) or CDMA-2000. The TDMA can beimplemented with a radio technology such as global system for mobilecommunications (GSM)/general packet ratio service (GPRS)/enhanced datarate for GSM evolution (EDGE). The OFDMA can be implemented with a radiotechnology such as institute of electrical and electronics engineers(IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA(E-UTRA), etc. The UTRA is a part of a universal mobiletelecommunication system (UMTS). 3^(rd) generation partnership project(3GPP) long term evolution (LTE) is a part of an evolved UMTS (E-UMTS)using the E-UTRA. The 3GPP LTE uses the OFDMA in a downlink and uses theSC-FDMA in an uplink. LTE-advance (LTE-A) is an evolution of the 3GPPLTE.

For clarity, the following description will focus on the 3GPP LTE/LTE-A.However, technical features of the present invention are not limitedthereto.

FIG. 1 shows a radio communication system.

Referring to FIG. 1, a radio communication system 10 includes at leastone base station (BS) 11. Respective BSs 11 provide communicationservices to specific geographical regions (generally referred to ascells) 15 a, 15 b, and 15 c. The cell can be divided into a plurality ofregions (referred to as sectors). A user equipment (UE) 12 may be fixedor mobile, and may be referred to as another terminology, such as amobile station (MS), a user terminal (UT), a subscriber station (SS), awireless device, a personal digital assistant (PDA), a wireless modem, ahandheld device, etc. The BS 11 is generally a fixed station thatcommunicates with the UE 12 and may be referred to as anotherterminology, such as an evolved node-B (eNB), a base transceiver system(BTS), an access point, etc.

Hereinafter, a downlink (DL) implies communication from the BS to theUE, and an uplink (UL) implies communication from the UE to the BS. Inthe DL, a transmitter may be a part of the BS, and a receiver may be apart of the UE. In the UL, the transmitter may be a part of the UE, andthe receiver may be a part of the BS.

A heterogeneous network implies a network in which a relay station, afemto cell and/or a pico cell, and the like are deployed. In theheterogeneous network, the DL may imply communication from the BS to therelay station, the femto cell, or the pico cell. Further, the DL mayalso imply communication from the relay station to the UE. Furthermore,in case of multi-hop relay, the DL may imply communication from a firstrelay station to a second relay station. In the heterogeneous network,the UL may imply communication from the relay station, the femto cell,or the pico cell to the BS. Further, the UL may also imply communicationfrom the UE to the relay station. Furthermore, in case of multi-hoprelay, the UL may imply communication from the second relay station tothe first relay station.

The radio communication system may be any one of a multiple inputmultiple output (MIMO) system, a multiple input single output (MISO)system, a single input single output (SISO) system, and a single inputmultiple output (SIMO) system. The MIMO system uses a plurality oftransmit antennas and a plurality of receive antennas. The MISO systemuses a plurality of transmit antennas and one receive antenna. The SISOsystem uses one transmit antenna and one receive antenna. The SIMOsystem uses one transmit antenna and a plurality of receive antennas.

Hereinafter, the transmit antenna denotes a physical or logical antennaused for transmission of one signal or stream. The receive antennadenotes a physical or logical antenna used for reception of one signalor stream.

UL and/or DL hybrid automatic repeat request (HARQ) can be supported inthe radio communication system. In addition, a channel quality indicator(CQI) can be used for link adaptation.

FIG. 2 shows HARQ acknowledgement (ACK)/not-acknowledgement (NACK) andCQI transmission.

Referring to FIG. 2, upon receiving DL data from a BS, a UE transmits anHARQ ACK/NACK after a specific time elapses. The DL data may betransmitted on a physical downlink shared channel (PDSCH) indicated by aphysical downlink control channel (PDCCH). The HARQ ACK/NACK correspondsto an ACK when the DL data is successfully decoded, and corresponds toan NACK when the DL data fails in decoding. Upon receiving the NACK, theBS can transmit the DL data until the ACK is received or untilretransmission is performed up to a maximum number of retransmissionattempts.

A transmission time of the HARQ ACK/NACK for the DL data or resourceallocation information for HARQ ACK/NACK transmission may be dynamicallyreported by the BS by using signaling. Alternatively, the transmissiontime of the HARQ ACK/NACK, the resource allocation information, etc.,may be pre-agreed according to the transmission time of the DL data orresource used for transmission of the DL data. For example, when a PDSCHis received on an n^(th) subframe in a frequency division duplex (FDD)system, an HARQ ACK/NACK for the PDSCH may be transmitted on a physicaluplink control channel (PUCCH) in an (n+4)^(th) subframe.

The UE may measure a DL channel state and report a CQI to the BSperiodically and/or non-periodically. The BS may use the CQI in DLscheduling. The BS may use the CQI received from the UE to determine amodulation and coding scheme (MCS) used in transmission. If it isdetermined that the channel state is good by using the CQI, the BS mayperform transmission by increasing a modulation order or by increasing acoding rate. If it is determined that the channel state is not good byusing the CQI, the BS may decrease a data rate by decreasing themodulation order or by decreasing the coding rate. A reception errorrate may decrease when the data rate decreases. The CQI may indicate achannel state for a full band and/or a channel state for some parts ofthe full band. The BS may report information on a transmission time ofthe CQI or resource allocation information for CQI transmission to theUE.

In addition to the CQI, the UE may report a precoding matrix indicator(PMI), a rank indicator (RI), etc., to the BS. The PMI indicates anindex of a precoding matrix selected from a codebook. The RI indicatesthe number of useful transmission layers. Hereinafter, the CQI is theconcept of including not only the CQI but also the PMI and the RI.

FIG. 3 shows UL transmission.

Referring to FIG. 3, for UL transmission, a UE first transmits ascheduling request (SR) to a BS. The SR is used when the UE requests theBS to allocate UL radio resources. The SR can also be referred to as abandwidth request. The SR is a sort of preliminary information exchangefor data exchange. In order for the UE to transmit UL data to the BS,the UE firsts requests allocation of the radio resources by using theSR. The BS may report to the UE a transmission time of the SR orresource allocation information for SR transmission. The SR may beperiodically transmitted. The BS may report to the UE a transmissionperiod of the SR.

In response to the SR, the BS sends a UL grant to the UE. The UL grantmay be transmitted on a PDCCH. The UL grant includes information on ULradio resource allocation. The UE transmits UL data by using theallocated UL radio resource.

As shown in FIG. 2 and FIG. 3, the UE can transmit UL controlinformation (e.g., an HARQ ACK/NACK, a CQI, and an SR) in a giventransmission time. A type and size of the UL control information mayvary depending on a system, and technical features of the presentinvention are not limited thereto.

FIG. 4 shows a structure of a radio frame in 3GPP LTE.

Referring to FIG. 4, the radio frame consists of 10 subframes. Onesubframe consists of two slots. Slots included in the radio frame arenumbered with slot numbers #0 to #19. A time required to transmit onesubframe is defined as a transmission time interval (TTI). The TTI maybe a scheduling unit for data transmission. For example, one radio framemay have a length of 10 milliseconds (ms), one subframe may have alength of 1 ms, and one slot may have a length of 0.5 ms.

The radio frame of FIG. 4 is shown for exemplary purposes only. Thus,the number of subframes included in the radio frame or the number ofslots included in the subframe may change variously.

FIG. 5 shows an example of a resource grid for one UL slot in 3GPP LTE.

Referring to FIG. 5, the UL slot includes a plurality of OFDM symbols ina time domain, and includes N^(UL) resource blocks (RBs) in a frequencydomain. The OFDM symbol represents one symbol period. The OFDM symbolcan apply to a multiple access scheme such as OFDMA, SC-FDMA, clusteredSC-FDMA, N×SC-FDMA, or the like. The OFDM symbol can also be referred toas an SC-FDMA symbol, an OFDMA symbol, or a symbol period according to asystem.

The RB includes a plurality of subcarriers in the frequency domain. Thenumber N^(UL) of RBs included in the UL slot depends on a ULtransmission bandwidth defined in a cell.

Each element on the resource grid is referred to as a resource element.The resource element on the resource grid can be identified by an indexpair (k, l) within the slot. Herein, k(k=0, . . . , N^(UL)×12−1) denotesa subcarrier index in the frequency domain, and l(l=0, . . . , 6)denotes a symbol index in the time domain.

Although it is described herein that one RB includes 7×12 resourceelements consisting of 7 OFDM symbols in the time domain and 12subcarriers in the frequency domain for example, the number of OFDMsymbols and the number of subcarriers in the RB are not limited thereto.Thus, the number of subcarriers or the number of OFDM symbols includedin the RB may change variously. Hereinafter, the RB implies a typicalfrequency resource. That is, if the RB differs, the frequency resourcealso differs. The number of OFDM symbols may change depending on acyclic prefix (CP) length. For example, when using a normal CP, thenumber of OFDM symbols is 7, and when using an extended CP, the numberof OFDM symbols is 6.

The resource grid for one UL slot in the 3GPP LTE of FIG. 5 can directlyapply to a resource grid for a DL slot.

FIG. 6 shows an example of a DL subframe structure in 3GPP LTE.

Referring to FIG. 6, a DL subframe includes two consecutive slots. Up tothree preceding OFDM symbols of a first slot in the DL subframecorrespond to a control region. The remaining OFDM symbols correspond toa data region.

A PDSCH may be allocated to the data region. DL data is transmitted onthe PDSCH. The DL data may be a transport block, i.e., a data block fora downlink shared channel (DL-SCH) which is a transport channeltransmitted during a TTI. A BS may transmit to a UE the DL data througha single antenna or multiple antennas. In the 3GPP LTE, the BS maytransmit to the UE one codeword through the single antenna or themultiple antennas, or may transmit two codewords through the multipleantennas. That is, up to two codewords are supported in the 3GPP LTE.The codewords are coded bits obtained by performing channel coding on aninformation bit corresponding to information. Modulation may beperformed on each codeword.

Examples of a control channel that can be allocated to the controlregion include a physical control format indicator channel (PCFICH), aphysical HARQ indicator channel (PHICH), a PDCCH, etc.

The PCFICH carries information indicating the number of OFDM symbolsused for transmission of PDCCHs in a subframe. Herein, the controlregion includes 3 OFDM symbols for exemplary purposes only. The PHICHcarries an HARQ ACK/NACK for UL transmission.

The control region consists of a set of a plurality of control channelelements (CCEs). If a total number of CCEs constituting a CCE set isN(CCE) in the DL subframe, the CCEs are indexed from 0 to N(CCE)-1. TheCCEs correspond to a plurality of resource elements groups. The resourceelement group is used to define mapping of the control channel toresource elements. One resource element group consists of a plurality ofresource elements. A PDCCH is transmitted on an aggregation of one orseveral contiguous CCEs. A plurality of PDCCHs may be transmitted in thecontrol region.

The PDCCH carries DL control information such as DL schedulinginformation, UL scheduling information, or UL power control commands.When the BS transmits DL data on the PDSCH in a subframe to the UE, theBS carries DL control information used for scheduling of the PDSCH onthe PDCCH in the subframe. The UE may read the DL data transmitted onthe PDSCH by decoding the DL control information.

FIG. 7 shows an example of a UL subframe structure in 3GPP LTE.

Referring to FIG. 7, a UL subframe can be divided into a control regionto which a PUCCH for carrying UL control information is allocated and adata region to which a physical uplink shared channel (PUSCH) forcarrying UL data is allocated. In 3GPP LTE (Release 8), RBs allocated toone UE are contiguous in a frequency domain in order to maintain asingle-carrier property. One UE cannot concurrently transmit the PUCCHand the PUSCH. Concurrent transmission of the PUCCH and the PUSCH aretaken into account in LTE-A (Release 10).

The PUCCH for one UE is allocated in an RB pair. RBs belonging to the RBpair occupy different subcarriers in each of a first slot and a secondslot. A frequency occupied by the RBs belonging to the RB pair allocatedto the PUCCH changes at a slot boundary. That is, the RBs allocated tothe PUCCH are hopped in a slot level. Hereinafter, hopping of RBs in theslot level is referred to as frequency hopping. Since the UE transmitsUL control information over time at a frequency located in a differentposition, a frequency diversity gain can be obtained. In FIG. 7, m is alocation index indicating a logical frequency-domain location of the RBpair allocated to the PUCCH in the subframe.

The PUSCH is mapped to an uplink shared channel (UL-SCH) that is atransport channel. Examples of the UL control information transmitted onthe PUCCH include an HARQ ACK/NACK, a CQI indicating a DL channel state,an SR that is a UL radio resource allocation request, etc.

The PUCCH can support multiple formats. That is, UL control informationhaving a different number of bits per subframe can be transmittedaccording to a modulation scheme depending on an application of thePUCCH format. Table 1 below shows an example of the modulation schemedepending on the PUCCH format and the number of bits per subframe.

TABLE 1 PUCCH Modulation Number of bits per format scheme subframe 1 N/AN/A 1a BPSK 1 1b QPSK 2 2 QPSK 20 2a QPSK + BPSK 21 2b QPSK + QPSK 22

The PUCCH format 1 is used to transmit the SR. The PUCCH formats 1a/1bare used to transmit the HARQ ACK/NACK. The PUCCH format 2 is used totransmit the CQI. The PUCCH formats 2a/2b are used to transmit the CQIand the HARQ ACK/NACK.

In any subframe, if the HARQ ACK/NACK is transmitted alone, the PUCCHformats 1a/1b are used, and if the SR is transmitted alone, the PUCCHformat 1 is used. The UE can concurrently transmit the HARQ ACK/NACK andthe SR. For positive SR transmission, the UE transmits the HARQ ACK/NACKby using a PUCCH resource allocated for the SR. For negative SRtransmission, the UE transmits the HARQ ACK/NACK by using a PUCCHresource allocated for the ACK/NACK.

Control information transmitted on the PUCCH uses a cyclically shiftedsequence. The cyclically shifted sequence may be generated by cyclicallyshifting a base sequence by a specific cyclic shift (CS) amount. Thespecific CS amount is indicated by a CS index. Various types ofsequences may be used as the base sequence. For example, well-knownsequences (e.g., a pseudo-random (PN) sequence and a Zadoff-Chu (ZC)sequence) may be used as the base sequence. In addition, a computergenerated constant amplitude zero auto-correlation (CAZAC) sequence maybe used as the base sequence. Equation 1 below shows an example of thebase sequence.

r _(i)(n)e ^(jb(n)π/4)  [Equation 1]

In Equation 1, iε{0, 1, . . . , 29} denotes a root index, and n denotesan element index satisfying 0≦n≦N−1, where N is a length of the basesequence. i denotes a cell identifier (ID), and may be determined by aslot number or the like within a radio frame. If one RB includes 12subcarriers, N may be set to 12. A different root index defines adifferent base sequence. If N=12, b(n) can be defined by Table 2 below.

TABLE 2 i b(0), . . . , b(11) 0 −1 1 3 −3 3 3 1 1 3 1 −3 3 1 1 1 3 3 3−1 1 −3 −3 1 −3 3 2 1 1 −3 −3 −3 −1 −3 −3 1 −3 1 −1 3 −1 1 1 1 1 −1 −3−3 1 −3 3 −1 4 −1 3 1 −1 1 −1 −3 −1 1 −1 1 3 5 1 −3 3 −1 −1 1 1 −1 −1 3−3 1 6 −1 3 −3 −3 −3 3 1 −1 3 3 −3 1 7 −3 −1 −1 −1 1 −3 3 −1 1 −3 3 1 81 −3 3 1 −1 −1 −1 1 1 3 −1 1 9 1 −3 −1 3 3 −1 −3 1 1 1 1 1 10 −1 3 −1 11 −3 −3 −1 −3 −3 3 −1 11 3 1 −1 −1 3 3 −3 1 3 1 3 3 12 1 −3 1 1 −3 1 1 1−3 −3 −3 1 13 3 3 −3 3 −3 1 1 3 −1 −3 3 3 14 −3 1 −1 −3 −1 3 1 3 3 3 −11 15 3 −1 1 −3 −1 −1 1 1 3 1 −1 −3 16 1 3 1 −1 1 3 3 3 −1 −1 3 −1 17 −31 1 3 −3 3 −3 −3 3 1 3 −1 18 −3 3 1 1 −3 1 −3 −3 −1 −1 1 −3 19 −1 3 1 31 −1 −1 3 −3 −1 −3 −1 20 −1 −3 1 1 1 1 3 1 −1 1 −3 −1 21 −1 3 −1 1 −3 −3−3 −3 −3 1 −1 −3 22 1 1 −3 −3 −3 −3 −1 3 −3 1 −3 3 23 1 1 −1 −3 −1 −3 1−1 1 3 −1 1 24 1 1 3 1 3 3 −1 1 −1 −3 −3 1 25 1 −3 3 3 1 3 3 1 −3 −1 −13 26 1 3 −3 −3 3 −3 1 −1 −1 3 −1 −3 27 −3 −1 −3 −1 −3 3 1 −1 1 3 −3 −328 −1 3 −3 3 −1 3 3 −3 3 3 −1 −1 29 3 −3 −3 −1 −1 −3 −1 3 −3 3 1 −1

A cyclically shifted sequence r(n, Ics) may be generated by cyclicallyshifting a base sequence r(n) according to Equation 2 below.

$\begin{matrix}{{{r\left( {n,I_{cs}} \right)} = {{r(n)} \cdot {\exp\left( \frac{{j2\pi}\; I_{cs}n}{N} \right)}}},{0 \leq I_{cs} \leq {N - 1}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

In Equation 2, Ics denotes a CS index indicating a CS amount (0≦Ics≦N−1,where Ics is an integer).

Hereinafter, an available CS index of the base sequence is defined as aCS index that may be derived from the base sequence according to a CSinterval. For one example, if the base sequence has a length of 12 andthe CS interval is 1, a total number of available CS indices is 12. Foranother example, if the base sequence has a length of 12 and the CSinterval is 2, a total number of available CS indices is 6. The CSinterval may be determined by considering a delay spread.

FIG. 8 shows an example of PUCCH format 1/1a/1b transmission when anormal CP is used. Herein, an RB pair allocated to a first slot and asecond slot in one subframe is shown. Although it is shown herein thatRBs belonging to the RB pair occupy the same frequency band in the firstslot and the second slot, the RBs can be hopped in a slot level asdescribed in FIG. 7.

Referring to FIG. 8, each of the first slot and the second slot includes7 OFDM symbols. Among the 7 OFDM symbols of each slot, a referencesignal (RS) is carried on 3 OFDM symbols, and control information iscarried on the remaining 4 OFDM symbols. The RS is carried on 3contiguous OFDM symbols positioned in a middle portion of each slot. Inthis case, the position and the number of symbols used for the RS mayvary, and thus the position and the number of symbols used for thecontrol information may also vary.

Each of the PUCCH formats 1, 1a, and 1b uses one complex-valued symbold(0). A BS can detect an SR according to presence/absence of PUCCHformat 1 transmission from a UE. That is, on-off keying (OOK) modulationscheme may be used in SR transmission. Therefore, any complex number canbe used as the complex-valued symbol d(0) for the PUCCH format 1. Forexample, d(0)=1 can be used. The complex-valued symbol d(0) for thePUCCH format 1a is a modulation symbol generated when 1-bit HARQACK/NACK information is modulated using binary phase shift keying(BPSK). The complex-valued symbol d(0) for the PUCCH format 1b is amodulation symbol generated when 2-bit HARQ ACK/NACK information ismodulated using quadrature phase shift keying (QPSK). The PUCCH format1a is for HARQ ACK/NACK information on one codeword. The PUCCH format 1bis for HARQ ACK/NACK information on two codewords.

Table 3 below shows an example of a modulation symbol to which an HARQACK/NACK information bit is mapped according to a modulation scheme.

TABLE 3 Modulation scheme Information bit(s) d(0) BPSK 0 1 1 −1 QPSK 001 01 −j 10 j 11 −1

A modulated sequence s(n) is generated by using the complex-valuedsymbol d(0) for the PUCCH formats 1/1a/1b and the cyclically shiftedsequence r(n,Ics). The modulated sequence s(n) may be generated bymultiplying the complex-valued symbol d(0) by the cyclically shiftedsequence r(n,Ics) according to Equation 3 below.

s(n)=d(0)r(n,I _(cs))  [Equation 3]

A CS index Ics of the cyclically shifted sequence r(n,Ics) may be hoppedin a symbol level, starting from an allocated resource. Hereinafter,hopping of the CS index in the symbol level is referred to as CShopping. The CS hopping can be performed according to a slot numbern_(s) within a radio frame and a symbol index f within a slot.Therefore, the CS index Ics can be expressed by Ics(n_(s),l). The CShopping can be performed in a cell-specific manner in order to randomizeinter-cell interference. Herein, a slot number of the first slot is setto 0, a slot number of the second slot is set to 1, and the CS index isset to Ics(0,0)=0, Ics(0,1)=1, Ics(0,5)=2, Ics(0,6)=3, Ics(1,0)=4,Ics(1,1)=5, Ics(1,5)=6, and Ics(1,6)=7. However, this is for exemplarypurposes only.

To increase UE multiplexing capacity, the modulated sequence s(n) may bespread by using an orthogonal sequence. The UE multiplexing capacitydenotes the number of UEs that can be multiplexed to the same RB.

Herein, it is shown that the modulated sequence s(n) is spread by usingan orthogonal sequence w(k) having a spreading factor K=4 with respectto 4 OFDM symbols for carrying control information within one slot. Anorthogonal sequence w_(Ios)(k) having a spreading factor K=4 (where Iosis an orthogonal sequence (OS) index, k is an element index of anorthogonal sequence, (0≦k≦K−1) may use a sequence as shown in Table 4below.

TABLE 4 Orthogonal sequence index [w(0), w(1), w(2), w(3)] 0 [+1 +1 +1+1] 1 [+1 −1 +1 −1] 2 [+1 −1 −1 +1]

Elements constituting the orthogonal sequence sequentially correspond ina one-to-one manner to OFDM symbols for carrying control information.Each element of the orthogonal sequence is multiplied by the modulatedsequence s(n) carried on its corresponding OFDM symbol to generate aspread sequence. The spread sequence is mapped to an RB pair allocatedto a PUCCH in a subframe. After the spread sequence is mapped to the RBpair, IFFT is performed on each OFDM symbol of the subframe to output atime-domain signal for the control information. Although the orthogonalsequence is multiplied before the IFFT is performed, the same result canalso be obtained when the orthogonal sequence is multiplied afterperforming the IFFT on the modulated sequence s(n).

Alternatively, the orthogonal sequence w_(Ios)(k) having a spreadingfactor K=3 (where Ios is an OS index, k is an element index of anorthogonal sequence, 0≦k≦K−1) may use a sequence as shown in Table 5below.

TABLE 5 Orthogonal sequence index [w(0), w(1), w(2)] 0 [1 1 1] 1 [1e^(j2π/3) e^(j4π/3)] 2 [1 e^(j4π/3) e^(j2π/3)]

When a sounding reference signal (SRS) and the PUCCH formats 1/1a/1b areconcurrently transmitted in one subframe, one OFDM symbol on the PUCCHis punctured. For example, a last OFDM symbol of the subframe may bepunctured. In this case, in a first slot of the subframe, the controlinformation is carried on 4 OFDM symbols. In a second slot of thesubframe, the control information is carried on 3 OFDM symbols.Therefore, the orthogonal sequence having the spreading factor K=4 isused for the first slot, and the orthogonal sequence having thespreading factor K=3 is used for the second slot.

The OS index may be hopped in a slot level, starting from an allocatedresource. Hereinafter, hopping of the OS index in the slot level isreferred to as OS remapping. The OS remapping can be performed accordingto the slot number n_(s) within the radio frame. Therefore, the OS indexIos can be expressed by Ios(n_(s)). The OS remapping may be performed torandomize inter-cell interference.

The modulated sequence s(n) may be subjected to scrambling in additionto spreading using the orthogonal sequence. For example, the modulatedsequence s(n) may be multiplied by 1 or j according to a specificparameter.

The RS can be generated based on the orthogonal sequence and thecyclically shifted sequence generated from the same base sequence as thecontrol information. The cyclically shifted sequence may be used as theRS by spreading the cyclically shifted sequence by the use of theorthogonal sequence w(k) having a spreading factor K=3. Therefore, inorder for the UE to transmit the control information, in addition to theOS index and the CS index for the control information, the OS index andthe CS index for the RS are also required.

FIG. 9 shows an example of PUCCH format 1/1a/1b transmission when anextended CP is used. Although it is shown herein that RBs belonging toan RB pair occupy the same frequency band in a first slot and a secondslot, the RBs may be hopped in a slot level as described in FIG. 7.

Referring to FIG. 9, each of the first slot and the second slot includes6 OFDM symbols. Among the 6 OFDM symbols of each slot, an RS is carriedon 2 OFDM symbols, and control information is carried on the remaining 4OFDM symbols. Other than that, the example of FIG. 8 in which the normalCP is used can be applied without alteration. However, the RS can beused by spreading the cyclically shifted sequence by the use of anorthogonal sequence w(k) having a spreading factor K=2.

An orthogonal sequence w_(Ios)(k) having a spreading factor K=2 (whereIos is an OS index, k is an element index of an orthogonal sequence,0≦k≦K−1) may use a sequence as shown in Table 6 below.

TABLE 6 Orthogonal sequence index [w(0), w(1)] 0 [1 1] 1 [1 −1] 2 N/A

As described above, in both cases of the normal CP and the extended CP,the following information is necessary for PUCCH format 1/1a/1btransmission. That is, a subcarrier (or RB) for transmitting the controlinformation, a CS index Ics and an OS index Ios for the controlinformation, and a CS index I'cs and an OS index I'os for the RS arenecessary. For example, when a CS interval is 2 in the extended CP, theUE multiplexing capacity is as follows. Since the number of CS indicesIcs and the number of OS indices Ios for the control information arerespectively 6 and 3, 18 UEs can be multiplexed per one RB. However, thenumber of CS indices I'cs and the number of OS indices I'os for the RSare respective 6 and 2, 12 UEs can be multiplexed per one RB. Therefore,the UE multiplexing capacity is limited by an RS part rather than acontrol information part.

FIG. 10 shows an example of PUCCH format 2/2a/2b transmission when anormal CP is used. Although it is shown herein that RBs belonging to anRB pair occupy the same frequency band in a first slot and a secondslot, the RBs may be hopped in a slot level as described in FIG. 7.

Referring to FIG. 10, among 7 OFDM symbols included in each slot, an RSis carried on 2 OFDM symbols and a CQI is carried on the remaining 5OFDM symbols. In this case, the number and locations of symbols used forthe RS may change, and the number and locations of symbols used for theCQI may also change.

A UE generates a coded CQI bit by performing channel coding on a CQIinformation bit. In this case, a block code may be used. A Reed-Mullercode family is one example of the block code. In 3GPP LTE, a (20, A)block code is used, where A is a size of the CQI information bit. Thatis, in the 3GPP LTE, a 20-bit coded CQI bit is generated alwaysirrespective of the size of the CQI information bit.

Table 7 below shows an example of 13 basis sequences for the (20, A)block code.

TABLE 7 i M_(1,0) M_(1,1) M_(1,2) M_(1,3) M_(1,4) M_(1,5) M_(1,6)M_(1,7) M_(1,8) M_(1,9) M_(1,10) M_(1,11) M_(1,12) 0 1 1 0 0 0 0 0 0 0 01 1 0 1 1 1 1 0 0 0 0 0 0 1 1 1 0 2 1 0 0 1 0 0 1 0 1 1 1 1 1 3 1 0 1 10 0 0 0 1 0 1 1 1 4 1 1 1 1 0 0 0 1 0 0 1 1 1 5 1 1 0 0 1 0 1 1 1 0 1 11 6 1 0 1 0 1 0 1 0 1 1 1 1 1 7 1 0 0 1 1 0 0 1 1 0 1 1 1 8 1 1 0 1 1 00 1 0 1 1 1 1 9 1 0 1 1 1 0 1 0 0 1 1 1 1 10 1 0 1 0 0 1 1 1 0 1 1 1 111 1 1 1 0 0 1 1 0 1 0 1 1 1 12 1 0 0 1 0 1 0 1 1 1 1 1 1 13 1 1 0 1 0 10 1 0 1 1 1 1 14 1 0 0 0 1 1 0 1 0 0 1 0 1 15 1 1 0 0 1 1 1 1 0 1 1 0 116 1 1 1 0 1 1 1 0 0 1 0 1 1 17 1 0 0 1 1 1 0 0 1 0 0 1 1 18 1 1 0 1 1 11 1 0 0 0 0 0 19 1 0 0 0 0 1 1 0 0 0 0 0 0

In Table 7, denotes a basis sequence (where 0≦n≦12, n is an integer).The coded CQI bit is generated by linear combination of the 13 basissequences. Equation 4 below shows an example of the encoded CQI bitb_(i) (where 0≦i≦19, i is an integer).

$\begin{matrix}{b_{i} = {\sum\limits_{n = 0}^{A - 1}\; {\left( {a_{n} \cdot M_{i,n}} \right)\mspace{14mu} {mod}\mspace{14mu} 2}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

In Equation 4, a₀, a₁, . . . , a_(A-1) denotes the CQI information bit,and A denotes the size of the CQI information bit (where A is a naturalnumber).

The CQI information bit may include one or more fields. Examples of thefields that can be included in the CQI information bit include a CQIfield indicating a CQI index for determining an MCS, a precoding matrixindication (PMI) field indicating an index of a precoding matrixselected from a codebook, a rank indication (RI) field indicating arank, etc.

Table 8 below shows an example of a field included in the CQIinformation bit and a bit size of the field.

TABLE 8 Field Size (bit) Wideband CQI 4

The CQI information bit may include only a 4-bit wideband CQI field. Inthis case, the size A of the CQI information bit is 4. The wideband CQIfield indicates a CQI index for a full band.

Table 9 below shows another example of a field included in the CQIinformation bit and a bit size of the field.

TABLE 9 Size (bit) 2 antennas 4 antennas Field Rank = 1 Rank = 2 Rank =1 Rank > 1 Wideband CQI 4 4 4 4 Spatial differential CQI 0 3 0 3Precoding matrix 2 1 4 4 indication

The CQI information bit may include a wideband CQI field, a spatialdifferential CQI field, and a PMI field. The spatial differential CQIfield indicates a difference between a CQI index for a full band for afirst codeword and a CQI index for a full band for a second codeword. Asize of each field may differ depending on a rank and the number oftransmit antennas of a BS. For example, if the BS uses 4 transmitantennas and the rank is greater than 1, the CQI information bitincludes a 4-bit wideband CQI field, a 3-bit spatial difference CQIfield, and a 4-bit PMI field (A=11).

Table 10 below shows another example of a field included in the CQIinformation bit and a bit size of the field.

TABLE 10 Size (bit) 4 antennas Field 2 antennas Max 2 layers Max 4layers Rank indication 1 1 2

A 20-bit coded CQI bit may be scrambled by using a UE-specificscrambling sequence to generate a 20-bit scrambled bit. The 20-bitscrambled bit is mapped to 10 modulation symbols d(0), . . . , d(9) byusing QPSK modulation. In the PUCCH format 2a, 1-bit HARQ ACK/NACKinformation is mapped to one modulation symbol d(10) by using BPSKmodulation. In the PUCCH format 2b, 2-bit HARQ ACK/NACK information ismapped to one modulation symbol d(10) by using QPSK modulation. That is,in the PUCCH format 2a, the CQI and the 1-bit HARQ ACK/NACK informationare concurrently transmitted, and in the PUCCH format 2b, the CQI andthe 2-bit HARQ ACK/NACK information are concurrently transmitted.Herein, d(10) is used for RS generation. d(10) corresponds to one OFDMsymbol between two OFDM symbols on which an RS is carried in each slot.In other words, according to d(10), phase modulation is performed on theRS carried on one OFDM symbol in each slot. The PUCCH formats 2a/2b canbe supported only for the normal CP. As such, in each of the PUCCHformats 2a and 2b, one modulation symbol is used for RS generation.

A modulated sequence is generated based on a cyclically shifted sequencer(n,Ics) generated from the modulation symbols d(0), . . . , d(9) and abase sequence. A CS index Ics of the cyclically shifted sequencer(n,Ics) may vary depending on a slot number n_(s) within a radio frameand a symbol index l within a slot. Therefore, the CS index Ics can beexpressed by Ics(n_(s),l). Herein, a slot number of the first slot isset to 0, a slot number of the second slot is set to 1, and the CS indexis set to Ics(0,0)=0, Ics(0,2)=1, Ics(0,3)=2, Ics(0,4)=3, Ics(0,6)=4,Ics(1,0)=5, Ics(1,2)=6, Ics(1,3)=7, Ics(1,4)=8, and Ics(1,6)=9. However,this is for exemplary purposes only. An RS may use a cyclically shiftedsequence generated from the same base sequence as control information.

Unlike the PUCCH formats 1/1a/1b, the PUCCH formats 2/2a/2b do not usean orthogonal sequence.

FIG. 11 shows an example of PUCCH format 2/2a/2b transmission when anextended CP is used. Although it is shown herein that RBs belonging toan RB pair occupy the same frequency band in a first slot and a secondslot, the RBs may be hopped in a slot level as described in FIG. 7.

Referring to FIG. 11, each of the first slot and the second slotincludes 6 OFDM symbols. Among the 6 OFDM symbols of each slot, an RS iscarried on one OFDM symbol, and control information is carried on theremaining 5 OFDM symbols. Other than that, the example of FIG. 10 inwhich the normal CP is used is applied without alteration.

As described above, in both cases of the normal CP and the extended CP,the following information is necessary for PUCCH format 2/2a/2btransmission. A subcarrier (or RB) for transmitting the controlinformation, a CS index Ics for the control information, and a CS indexI'cs for the RS are necessary. When a CS interval is 1, the number ofindices Ics for the control information and the number of indices I'csfor the RS are 12 each, and thus 12 UEs can be multiplexed per one RB.When the CS interval is 2, the number of indices Ics for the controlinformation and the number of indices I'cs for the RS are 6 each, andthus 6 UEs can be multiplexed per one RB.

FIG. 12 is a flowchart showing an example of an information transmissionmethod.

Referring to FIG. 12, a UE obtains a resource index (step S11). The UEprocesses information on the basis of the resource index (step S12). TheUE transmits the information to a BS (step S13).

A plurality of UEs in a cell can concurrently transmit their informationto the BS. In this case, if each UE uses a different resource, the BScan identify information of each UE. The information may be controlinformation, user data, information in which several pieces of controlinformation are mixed, information in which the control information andthe user data are multiplexed, etc.

A resource may include at least one of an RB, a frequency-domainsequence, and a time-domain sequence. The RB is a frequency resource forinformation transmission. The frequency-domain sequence is used tospread a symbol corresponding to the information to a frequency domain.The time-domain sequence is used to spread the symbol to a time domain.When the resource includes the frequency-domain sequence and thetime-domain sequence, the frequency-domain sequence and the time-domainsequence are used to spread the symbol to a 2 dimensional time-frequencydomain (i.e., the frequency domain and the time domain).

A resource index identifies a resource used for informationtransmission. According to the resource, the resource index may includeat least one of RB information, a frequency-domain sequence index, and atime-domain sequence index. The RB information indicates the RB, thefrequency-domain sequence index indicates the frequency-domain sequence,and the time-domain sequence index indicates the time-domain sequence.For example, when the resource includes the RB and the frequency-domainsequence, the resource index may include the RB information and thefrequency-domain sequence index.

Hereinafter, a sequence used as the frequency-domain sequence and/or thetime-domain sequence will be described in detail. The sequence may beselected from a sequence set having a plurality of sequences as itselements. The plurality of sequences included in the sequence set may beorthogonal to each other, or may have a low correlation with each other.

When the resource includes the sequence, the resource index may includethe sequence index. The sequence may be generated based on the sequenceindex. Hereinafter, the sequence is the frequency-domain sequence and/orthe time-domain sequence.

For one example, the sequence index may indicate one sequence selectedfrom the sequence set. Each sequence belonging to the sequence set mayone-to-one correspond to one sequence index.

For another example, a sequence index may indicate a CS amount, and asequence may be generated by cyclically shifting the base sequence bythe CS amount.

It is assumed hereinafter that the time-domain sequence is oneorthogonal sequence selected from a set of orthogonal sequences, and thefrequency-domain sequence is a cyclically shifted sequence generated bycyclically shifting the base sequence by the CS amount. In this case,the time-domain sequence index may be an OS index indicating anorthogonal sequence, and the frequency-domain sequence index may be a CSindex indicating a CS amount. However, this is for exemplary purposesonly, and is not for restricting the time-domain sequence and/or thefrequency-domain sequence.

In case of the PUCCH formats 1/1a/1b, the resource consists ofcombinations of (1) a CS amount, (2) an orthogonal sequence, and (3) anRB. A resource index indicates a CS index, an OS index, and the RB. Forexample, if the number of CS indices is 6, the number of OS indices is3, and the number of RBs is 3, then the total number of resources is54(=6×3×3). The 54 resources may be numbered with resource indices from0 to 53. Each of the 54 resources may be allocated to different UEs.

In case of the PUCCH formats 2/2a/2b, the resource consists ofcombinations of (1) a CS amount and (2) an RB. A resource indexindicates a CS index and the RB. For example, the number of CS indicesis 6 and the number of RBs is 2, the total number of resources is12(=6×2). The 12 resources may be numbered with resource indices from 0to 11. Each of the 12 resources may be allocated to different UEs.

As such, the CS index and the RB are determined from the resource index.In case of the PUCCH formats 1/1a/1b, the OS index is also determinedfrom the resource index. For example, a location index m indicating alogical frequency-domain location of an RB pair allocated to a PUCCH ina subframe may be determined from the resource index.

FIG. 13 is a flowchart showing another example of an informationtransmission method.

Referring to FIG. 13, a BS transmits a resource index to a UE (stepS21). The UE processes information on the basis of the resource index(step S22). The UE transmits the information to the BS (step S23). Assuch, the BS may explicitly report the resource index to the UE. Theresource index may be configured by higher-layer signaling. For example,a higher layer of a physical layer may be a radio resource control (RRC)layer that controls a radio resource between the UE and a network. Inthis case, information transmitted by the UE may be an SR,semi-persistent scheduling (SPS), an ACK/NACK, a CQI, etc. The SPSACK/NACK is an HARQ ACK/NACK for DL data transmitted using the SPS. Whenthe DL data is transmitted through a PDSCH, a PDCCH corresponding to thePDSCH may not exist.

FIG. 14 is a flowchart showing another example of an informationtransmission method.

Referring to FIG. 14, a BS transmits DL data to a UE (step S31). The UEobtains a resource index (step S32). In this case, the resource indexmay be obtained from a radio resource used to transmit a control channelfor receiving DL data. The UE processes information on the basis of theresource index (step S33). The UE transmits the information to the BS(step S34). As such, the BS may implicitly report the resource index tothe UE. In this case, information transmitted by the UE may be a dynamicACK/NACK. The dynamic ACK/NACK is an ACK/NACK for DL data transmittedusing dynamic scheduling. In the dynamic scheduling, a DL grant istransmitted to the UE through the PDCCH whenever the BS transmits DLdata through the PDSCH.

Equation 5 below shows an example of determining a resource index ‘In’for dynamic ACK/NACK transmission.

In=n(CCE)+N _(PUCCH) ⁽¹⁾  [Equation 5]

In Equation 5, n(CCE) denotes a first CCE index used in PDCCHtransmission for a PDSCH, and N⁽¹⁾ _(PUCCH) denotes the number ofresource indices allocated for an SR and an SPS ACK/NACK. N⁽¹⁾ _(PUCCH)may be determined by a higher layer such as an RRC layer.

Therefore, the BS can control a resource for ACK/NACK transmission bycontrolling the first CCE index used in PDCCH transmission.

FIG. 15 is a flowchart showing an example of an information processingmethod based on a resource index.

Referring to FIG. 15, a UE determines a CS index on the basis of theresource index (step S41). The UE generates a cyclically shiftedsequence on the basis of the CS index (step S42). The cyclically shiftedsequence may be generated by cyclically shifting a base sequence by a CSamount obtained from the CS index. The UE generates a modulated sequenceon the basis of the cyclically shifted sequence and a symbol forinformation (step S43). The UE maps the modulated sequence to an RB(step S44). The RB may be determined based on the resource index. The UEtransmits the modulated sequence. In this case, the informationtransmitted by the UE may be a CQI.

FIG. 16 is a flowchart showing another example of an informationprocessing method based on a resource index.

Referring to FIG. 16, a UE determines an OS index and a CS index on thebasis of the resource index (step S51). The UE generates a cyclicallyshifted sequence on the basis of the CS index (step S52). The UEgenerates a modulated sequence on the basis of the cyclically shiftedsequence and a symbol for information (step S53). The UE generates asequence spread from the modulated sequence on the basis of the OS index(step S54). The UE maps the spread sequence to an RB (step S55). The RBmay be determined on the basis of the resource index. The UE transmitsthe spread sequence. In this case, the information transmitted by the UEmay be an SR, an HARQ ACK/NACK, etc.

As described up to now, UL information for each of a plurality of UEs ina cell can be multiplexed in a subframe by using code divisionmultiplexing (CDM) and/or frequency division multiplexing (FDM). Theplurality of UEs can transmit information simultaneously to a BS byusing different resources. The BS may identify each UE's informationtransmitted simultaneously.

The UE may transmit the information through a plurality of transmit (Tx)antennas. Among MIMO techniques, a Tx diversity scheme has a diversitygain, and can increase reliability of radio communication. Examples ofthe Tx diversity scheme includes cyclic delay diversity (CDD), precodingvector switching (PVS), etc. However, the use of these schemes may causeproblems in that orthogonality is not maintained, a Tx diversity gain islimited, or backward compatibility with 3GPP LTE is not satisfied.Therefore, there is a need for a method of information transmission byusing the Tx diversity scheme capable of solving the aforementionedproblems.

FIG. 17 is a flowchart showing an information transmission methodaccording to an embodiment of the present invention.

Referring to FIG. 17, a UE generates 1^(st) and 2^(nd) symbolscorresponding to information (step S110). The UE generates 1^(st) and2^(nd) Tx vectors from the 1^(st) and 2^(nd) symbols on the basis of anAlamouti code (step S120). The UE transmits the 1^(st) Tx vector througha 1^(st) antenna, and transmits the 2^(nd) Tx vector through a 2^(nd)antenna (step S130). In this case, the 1^(st) Tx vector consists of1^(st) and 2^(nd) Tx symbols. The 1^(st) Tx symbol is transmitted basedon a 1^(st) resource index, and the 2^(nd) Tx symbol is transmittedbased on a 2^(nd) resource index. The 2^(nd) Tx vector consists of3^(rd) and 4^(th) Tx symbols. The 3^(rd) Tx symbol is transmitted basedon the 1^(st) resource index, and the 4^(th) Tx symbol is transmittedbased on the 2^(nd) resource index.

Space block coding (SBC) using a resource is used in the informationtransmission method. The UE may obtain a diversity gain by performingsmart repetition by using an antenna and a resource. A spatialmultiplexing rate is 1. Hereinafter, such an information transmissionmethod is referred to as an SBC information transmission method.

Each of the 1^(st) and 2^(nd) symbols may be one complex-valued symbolor a plurality of complex-valued symbols. A plurality of complex-valuedsymbols may be referred to as a sequence or a signal. The 1^(st) symboland the 2^(nd) symbol can be respectively referred to as a 1^(st) signaland a 2^(nd) signal. Each of the 1^(st) and 2^(nd) symbols may begenerated by modulating an information bit corresponding to information.In this case, each of the 1^(st) symbol and the 2^(nd) symbol may be onemodulation symbol or a plurality of modulation symbols. Herein, the1^(st) symbol may be referred to as a 1^(st) modulation symbol and the2^(nd) symbol may be referred to as a 2^(nd) modulation symbol.

The 1^(st) resource index and the 2^(nd) resource index are differentfrom each other. Since the 1^(st) resource index and the 2^(nd) resourceindex are different from each other, orthogonality may be maintainedbetween the Tx antennas. If the 1^(st) resource index and the 2^(nd)resource index are identical to each other, information may betransmitted through one antenna without having to transmit theinformation by using a Tx diversity scheme.

Each of the 1^(st) to 4^(th) Tx symbols can be transmitted in PUCCHformats 1/1a/1b or PUCCH formats 2/2a/2b. In addition to the PUCCHformats 1/1a/1b or the PUCCH formats 2/2a/2b, the SBC informationtransmission method is applicable to all CDM-based transmission methods.

The 1^(st) Tx symbol generates a 1^(st) Tx sequence based on the 1^(st)resource index. The 2^(nd) Tx symbol generates a 2^(nd) Tx sequencebased on the 2^(nd) resource index. The 3^(rd) Tx symbol generates a3^(rd) Tx sequence based on the 1^(st) resource index. The 4^(th) Txsymbol generates a 4^(th) Tx sequence based on the 2^(nd) resourceindex.

The 1^(st) Tx sequence and the 2^(nd) Tx sequence may be combined andtransmitted through the 1^(st) antenna. The 2^(nd) Tx sequence and the4^(th) Tx sequence may be combined and transmitted through the 2^(nd)antenna. To decrease a cubic metric (CM), a phase of at least one Txsequence may change when combining one Tx sequence to another Txsequence. For example, the UE may combine the 2^(nd) Tx sequence and the1^(st) Tx sequence by phase-shifting the 2^(nd) Tx sequence by aspecific phase. In addition, the UE may combine the 4^(th) Tx sequenceand the 3^(rd) Tx sequence by phase-shifting the 4^(th) Tx sequence bythe specific phase. In case of BPSK, the specific phase may be 90degrees. In case of QPSK, the specific phase may be 45 degrees.

For channel estimation for each of the 1^(st) and 2^(nd) antennas, tworesources have to be allocated to a reference signal (RS) part.Resources allocated to an information part are not one-to-one mapped tothe antennas, but resources allocated to the RS part can be one-to-onemapped to the antennas. When the resources allocated to the RS part areone-to-one mapped to the resources, it is possible to achieve orthogonalchannel estimation for each antenna.

In case of a normal cyclic prefix (CP) of the PUCCH formats 2/2a/2b, anRS is carried on 2 OFDM symbols in one slot. The 2 OFDM symbols on whichthe RS is carried are referred to as a 1^(st) RS symbol and a 2^(nd) RSsymbol, respectively. When information is transmitted using the SBCinformation transmission method through 2 Tx antennas by allocating tworesources, in the 1^(st) RS symbol, a 1^(st) resource may be transmittedthrough the 1^(st) antenna, and a 2^(nd) resource may be transmittedthrough the 2^(nd) antenna. In the 2^(nd) RS symbol, the 1^(st) resourcemay be transmitted through the 2^(nd) antenna, and the 2^(nd) resourcemay be transmitted through the 1^(st) antenna. That is, resourceswapping are achieved across two RS symbols. When each resource consistsof a different resource block (RB), channel estimation can be achievedfor each antenna of the RB. The resource swapping operation in a slotlevel may also be performed in a subframe level.

FIG. 18 is a block diagram showing a transmitter for implementing anembodiment of the present invention. The transmitter may be a part of anapparatus for radio communication. The apparatus for radio communicationmay be a UE or a BS.

Referring to FIG. 18, a transmitter 100 includes a modulator 110, an SBCprocessor 120, and two Tx antennas 190-1 and 190-2.

An information bit is input to the modulator 110. A plurality ofinformation bits are also referred to as a bit stream. Alternatively,coded bits obtained when a channel coding unit (not shown) performschannel coding on the information bit may be input to the modulator 110.The modulator 110 generates 1^(st) and 2^(nd) symbols by mapping theinformation bit to a modulation symbol representing a location on aconstellation.

The information bit corresponds to information to be transmitted by thetransmitter 100.

A modulation scheme is not limited to a particular scheme, and thus maybe m-phase shift keying (m-PSK) or m-quadrature amplitude modulation(m-QAM). Each of the 1^(st) and 2^(nd) symbols may be one or a pluralityof complex-valued modulation symbols.

Table 11 below shows an example of a 1^(st) symbol s₁ and a 2^(nd)symbol s₂ each of which is generated from the information bit accordingto the modulation scheme.

TABLE 11 Modulation scheme Information bit 1st symbol(s₁) 2ndsymbols(s₂) BPSK b(0), b(1) d(0) d(1) BPSK/QPSK b(0)/b(1), b(2) d(0)d(1) QPSK b(0), b(1), b(2), b(3) d(0) d(1) QPSK b(0), b(1), . . . ,d(0), d(1), . . . , d(10), d(11), . . . , b(39) d(9) d(19)

As such, the transmitted information bit may have various bit sizes.Different modulation scheme may be applied to the 1^(st) symbol and the2^(nd) symbol. For example, BPSK may be applied to the 1^(st) symbol,and QPSK may be applied to the 2^(nd) symbol. In addition to the exampleof Table 11 above, various modulation schemes may be used for theinformation bit with various bit sizes.

The information may be divided into 1^(st) information and 2^(nd)information. That is, the information may include the 1^(st) informationand the 2^(nd) information. In this case, the information bitcorresponding to the information is generated by combining the 1^(st)information and the 2^(nd) information.

Table 12 below shows a relation between the information bit and the1^(st)/2^(nd) information.

TABLE 12 Information bit 1st information 2nd information b(0), b(1) b(0)b(1) b(0), b(1), b(2) b(0) b(1), b(2) b(0), b(1) b(2) b(0), b(1), b(2),b(3) b(0), b(1) b(2), b(3) b(0), b(2) b(1), b(3) b(0), b(1), . . . ,b(39) b(0), b(1), b(2), . . . , b(19) b(20), b(21), b(22), . . . , b(39)b(0), b(2), b(4), . . . , b(38) b(1), b(3), b(5), . . . , b(39)

In addition to the example of Table 12 above, the 1^(st) information andthe 2^(nd) information may be combined in various manners to generatethe information bit. For example, the 1^(st) symbol may be a 1^(st)modulation symbol for the 1^(st) information, and the 2^(nd) symbol maybe a 2^(nd) modulation symbol for the 2^(nd) information.

Hereinafter, examples of the 1^(st) information and the 2^(nd)information will be described. The 1^(st) information and the 2^(nd)information may be different control information, different user data,etc.

For example, the 1^(st) information and the 2^(nd) information may becontrol information for different DL carriers. The 1^(st) informationmay be 1^(st) control information for a 1^(st) DL carrier, and the2^(nd) information may be 2^(nd) control information for a 2^(nd) DLcarrier. More specifically, the 1^(st) information may be a 1^(st)ACK/NACK for 1^(st) data transmitted on the 1^(st) DL carrier, and the2^(nd) information may be a 2^(nd) ACK/NACK for 2^(nd) data transmittedon the 2^(nd) DL carrier. Alternatively, the 1^(st) information may be a1^(st) CQI for the 1^(st) DL carrier, and the 2^(nd) information may bea 2^(nd) CQI for the 2^(nd) DL carrier. In this case, information foreach of the 1^(st) DL carrier and the 2^(nd) DL carrier may betransmitted on one UL carrier. Therefore, the SBC informationtransmission method may be used in an asymmetric multi-carrier system inwhich the number of DL carriers is greater than the number of ULcarriers. For example, the method can be used in a multiple-carriersystem in which a ratio of the number of DL carriers to the number of ULcarriers is 2:1.

For another example, the 1^(st) information and the 2^(nd) informationmay be control information for different codeword groups. Each codewordgroup includes at least one codeword. Each codeword group may include adifferent codeword. A 1^(st) codeword group may include a 1^(st)codeword, and a 2^(nd) codeword group may include a 2^(nd) codeword.Alternatively, the 1^(st) codeword group may include the 1^(st) codewordand the 2^(nd) codeword, and the 2^(nd) codeword group may include a3^(rd) codeword and a 4^(th) codeword. Alternatively, the 1^(st)codeword group may include the 1^(st) codeword, and the 2^(nd) codewordgroup may include the 2^(nd) codeword and the 3^(rd) codeword.

The 1^(st) information may be 1^(st) control information for the 1^(st)codeword group, and the 2^(nd) information may be 2^(nd) controlinformation for the 2^(nd) codeword group. More specifically, the 1^(st)information may be a 1^(st) CQI for the 1^(st) codeword group, and the2^(nd) information may be a 2^(nd) CQI for the 2^(nd) codeword group.Alternatively, the 1^(st) information may be a 1^(st) ACK/NACK for the1^(st) codeword group, and the 2^(nd) information may be a 2^(nd)ACK/NACK for the 2^(nd) codeword group.

For example, if there is a need to transmit HARQ ACK/NACK informationfor 4 codewords, HARQ ACK/NACK information for 2 codewords may betransmitted as the 1^(st) information and HARQ ACK/NACK information forthe remaining 2 codewords may be transmitted as the 2^(nd) information.Each of the 1^(st) information and the 2^(nd) information has a lengthof 2 bits. The 1^(st) information may be mapped to the 1^(st) symbol byusing QPSK modulation, and the 2^(nd) information may be mapped to the2^(nd) symbol by using QPSK modulation. As such, the PUCCH format 1b of3GPP LTE(Release 8) may be extendedly applied to transmit 4-bit HARQACK/NACK information.

A system supporting 4 codewords may have 2 DL carriers, and the numberof codewords for each DL carrier may be 2. A system supporting 2codewords may have 2 DL carriers, and the number of codewords for eachDL carrier may be 1.

For another example, each of the 1^(st) information and the 2^(nd)information may be representative information. The representativeinformation is one piece of information that represents a plurality ofpieces of information. When the plurality of pieces of information areindicated by one piece of representative information, it is calledinformation bundling. Examples of the representative information includea representative CQI, a representative ACK/NACK, a representative PMI,etc. The representative CQI may be one CQI for all of a plurality of DLcarriers. For example, the representative CQI may be an average CQI ofrespective CQIs for the plurality of DL carriers. Alternatively, therepresentative CQI may be one CQI representing the respective CQIs for aplurality of codewords. The representative ACK/NACK may be one HARQACK/NACK for individual data transmitted on the plurality of DLcarriers. For example, when individual data transmitted on the pluralityof DL carriers is successfully decoded, the representative ACK/NACK isan ACK, and otherwise, the representative ACK/NACK is an NACK.Alternatively, the representative ACK/NACK may be one HARQ ACK/NACKrepresenting respective ACKs/NACKs for the plurality of codewords. The1^(st) information may be 1^(st) representative information for a 1^(st)DL carrier group, and the 2^(nd) information may be 2^(nd)representative information for a 2^(nd) DL carrier group. The 1^(st) DLcarrier group may include the 1^(st) DL carrier and the 2^(nd) DLcarrier, and the 2^(nd) DL carrier group may include a 3^(rd) DL carrierand a 4^(th) DL carrier. Alternatively, the 1^(st) information may be1^(st) representative information for the 1^(st) codeword group, and the2^(nd) information may be 2^(nd) representative information for the2^(nd) codeword group.

Table 13 below shows an example of a constellation mapping method forgenerating a 1^(st) symbol (i.e., s₁=I₁+j Q₁) and a 2^(nd) symbol (i.e.,s₂=I₂+j Q₂) from a 4-bit information bit (i.e., b(0),b(1),b(2),b(3)).

TABLE 13 1st symbol(s₁) 2nd symbols(s₂) b(0), b(1), b(2), b(3) I₁ Q₁ I₂Q₂ 0000 −1/{square root over (2)} −1/{square root over (2)} 0 0 0001−1/{square root over (2)} 0 0 −1/{square root over (2)} 0010 0−1/{square root over (2)} −1/{square root over (2)} 0 0011 0 0−1/{square root over (2)} −1/{square root over (2)} 0100 −1/{square rootover (2)} 0 0  1/{square root over (2)} 0101 −1/{square root over (2)} 1/{square root over (2)} 0 0 0110 0 0 −1/{square root over (2)} 1/{square root over (2)} 0111 0  1/{square root over (2)} −1/{squareroot over (2)} 0 1000 0 −1/{square root over (2)}  1/{square root over(2)} 0 1001 0 0  1/{square root over (2)} −1/{square root over (2)} 1010 1/{square root over (2)} −1/{square root over (2)} 0 0 1011  1/{squareroot over (2)} 0 0 −1/{square root over (2)} 1100 0 0  1/{square rootover (2)}  1/{square root over (2)} 1101 0  1/{square root over (2)} 1/{square root over (2)} 0 1110  1/{square root over (2)} 0 0 1/{square root over (2)} 1111  1/{square root over (2)}  1/{square rootover (2)} 0 0

When the information bit is ‘0000’, the 2^(nd) symbol is 0. In thiscase, the 2^(nd) symbol is not transmitted, and only the 1^(st) symbolis transmitted.

The SBC processor 120 generates a 1^(st) Tx vector and a 2^(nd) Txvector on the basis of an Alamouti code from the 1^(st) and 2^(nd)symbols output from the modulator 110. The 1^(st) antenna 190-1transmits the 1^(st) Tx vector, and the 2^(nd) antenna 190-2 transmitsthe 2^(nd) Tx vector. The 1^(st) Tx vector consists of a 1^(st) Txsymbol and a 2^(nd) Tx symbol, and the 2^(nd) Tx vector consists of a3^(rd) Tx symbol and a 4^(th) Tx symbol. The 1^(st) Tx symbol istransmitted based on a 1^(st) resource index, and the 2^(nd) Tx symbolis transmitted based on a 2^(nd) resource index. The 3^(rd) Tx symbol istransmitted based on the 1^(st) resource index, and the 4^(th) Tx symbolis transmitted based on the 2^(nd) resource index.

Hereinafter, a Tx matrix is defined as a 2×2 matrix of which a 1″ columnis the 1^(st) Tx vector and a 2^(nd) column is the 2^(nd) Tx vector. Anelement of an i^(th) row and a j^(th) column of the Tx matrix isexpressed by (i,j) (where i=1, 2 and j=1,2). (1,1) and (2,1)respectively denote the 1^(st) Tx symbol and the 2^(nd) Tx symbol of the1^(st) Tx vector. (1,2) and (2,2) respectively denote the 3^(rd) Txsymbol and the 4^(th) Tx symbol of the 2^(nd) Tx vector. The 1^(st) Txsymbol and the 4^(th) Tx symbol have a complex conjugate relation. The2^(nd) Tx symbol and the 3^(rd) Tx symbol have a complex conjugaterelation. A negative sign is appended to any one of the 1^(st) Tx symbolto the 4^(th Tx) symbol.

Table 14 below shows various examples of the Tx matrix.

TABLE 14 (1) $\begin{bmatrix}s_{1} & s_{2} \\{- s_{2}^{*}} & s_{1}^{*}\end{bmatrix}\quad$ (5) $\begin{bmatrix}s_{1} & {- s_{2}} \\s_{2}^{*} & s_{1}^{*}\end{bmatrix}\quad$ (2) $\begin{bmatrix}s_{1}^{*} & s_{2} \\{- s_{2}^{*}} & s_{1}\end{bmatrix}\quad$ (6) $\begin{bmatrix}s_{1}^{*} & {- s_{2}} \\s_{2}^{*} & s_{1}\end{bmatrix}\quad$ (3) $\begin{bmatrix}s_{1} & s_{2}^{*} \\{- s_{2}} & s_{1}^{*}\end{bmatrix}\quad$ (7) $\begin{bmatrix}s_{1} & {- s_{2}^{*}} \\s_{2} & s_{1}^{*}\end{bmatrix}\quad$ (4) $\begin{bmatrix}s_{1}^{*} & s_{2}^{*} \\{- s_{2}} & s_{1}\end{bmatrix}\quad$ (8) $\begin{bmatrix}s_{1}^{*} & {- s_{2}^{*}} \\s_{2} & s_{1}\end{bmatrix}\quad$

In case of the example (7) of Table 14, the 1^(st) Tx symbol isgenerated based on the 1^(st) symbol, the 2^(nd) Tx symbol is generatedbased on the 2^(nd) symbol, the 3^(rd) Tx symbol is obtained byappending a negative sign to a complex conjugate of the 2^(nd) Txsymbol, and the 4^(th) Tx symbol is a complex conjugate of the 1^(st) Txsymbol.

Table 15 below shows another example of the Tx matrix.

TABLE 15 (1) $\begin{bmatrix}s_{1} & s_{2} \\s_{2}^{*} & {- s_{1}^{*}}\end{bmatrix}\quad$ (5) $\begin{bmatrix}{- s_{1}} & s_{2} \\s_{2}^{*} & s_{1}^{*}\end{bmatrix}\quad$ (2) $\begin{bmatrix}s_{1}^{*} & s_{2} \\s_{2}^{*} & {- s_{1}}\end{bmatrix}\quad$ (6) $\begin{bmatrix}{- s_{1}^{*}} & s_{2} \\s_{2}^{*} & s_{1}\end{bmatrix}\quad$ (3) $\begin{bmatrix}s_{1} & s_{2}^{*} \\s_{2} & {- s_{1}^{*}}\end{bmatrix}\quad$ (7) $\begin{bmatrix}{- s_{1}} & s_{2}^{*} \\s_{2} & s_{1}^{*}\end{bmatrix}\quad$ (4) $\begin{bmatrix}s_{1}^{*} & s_{2}^{*} \\s_{2} & {- s_{1}}\end{bmatrix}\quad$ (8) $\begin{bmatrix}{- s_{1}^{*}} & s_{2}^{*} \\s_{2} & s_{1}\end{bmatrix}\quad$

Referring to Table 15, the 3^(rd) Tx symbol is a complex conjugate ofthe 2^(nd) Tx symbol, and the 4^(th) Tx symbol is obtained by appendinga negative sign to a complex conjugate of the 1^(st) Tx symbol.

However, this is for exemplary purposes only. In addition to the casesshown in Tables 14 and 15, the Tx matrix generated based on the Alamouticode from the 1^(st) symbol and the 2^(nd) symbol may have variousformats.

A row and/or a column of the Tx matrix may correspond to a Tx antennaand a resource index. It is assumed hereinafter that rows of the matrixrespectively correspond to resource indices, and columns of the matrixrespectively correspond to Tx antennas. In this case, the 1^(st) Txsymbol is processed with the 1^(st) resource index, the 2^(nd) Tx symbolis processed with the 2^(nd) resource index, and then transmission isperformed through the 1^(st) antenna. The 3^(rd) Tx symbol is processedwith the 1^(st) resource index, the 4^(th) Tx symbol is processed withthe 2^(nd) resource index, and then transmission is performed throughthe 2^(nd) antenna.

Table 16 shows an example of a Tx matrix generated from a 4-bitinformation bit. Herein, a 1^(st) symbol s₁ and a 2^(nd) symbol s₂ aregenerated from the information bit according to Table 13 above, and theTx matrix is generated according to the example (1) of Table 14 above.

TABLE 16 Information bit 1st symbol(s₁) 2nd symbol(s₂) Transmit matrix0000 ${- \frac{1}{\sqrt{2}}} - {j\frac{1}{\sqrt{2}}}$ 0$\begin{bmatrix}{{- \frac{1}{\sqrt{2}}} - {j\frac{1}{\sqrt{2}}}} & 0 \\0 & {{- \frac{1}{\sqrt{2}}} + {j\frac{1}{\sqrt{2}}}}\end{bmatrix}\quad$ 0001 $- \frac{1}{\sqrt{2}}$${- j}\frac{1}{\sqrt{2}}$ $\begin{bmatrix}{- \frac{1}{\sqrt{2}}} & {{- j}\frac{1}{\sqrt{2}}} \\{{- j}\frac{1}{\sqrt{2}}} & {- \frac{1}{\sqrt{2}}}\end{bmatrix}\quad$ 0010 ${- j}\frac{1}{\sqrt{2}}$$- \frac{1}{\sqrt{2}}$ $\begin{bmatrix}{{- j}\frac{1}{\sqrt{2}}} & {- \frac{1}{\sqrt{2}}} \\{- \frac{1}{\sqrt{2}}} & {j\frac{1}{\sqrt{2}}}\end{bmatrix}\quad$

Referring to Table 16, if the information bit is ‘0000’, it isequivalent to the case (see Table 13) where the information bit ‘0000’is transmitted based on the 1^(st) resource index and the 2^(nd)resource index through the 1^(st) antenna, and the information bit‘0110’ is transmitted based on the 1^(st) resource index and the 2^(nd)resource index through the 2^(nd) antenna.

When Tx power is limited, a normalization factor corresponding to thenumber of Tx antennas may be used in general. Equation 6 below shows anexample of the normalization factor.

$\begin{matrix}\frac{1}{\sqrt{{Ntx} \times {Nc}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

In Equation 6, Ntx denotes the number of Tx antennas, and Nc denotes thenumber of resources per antenna.

A Tx matrix having the format of the example (7) of Table 14 can begenerated by Equation 7 below.

$\begin{matrix}{\begin{bmatrix}{s(1)} \\{s(2)} \\{s(3)} \\{s(4)}\end{bmatrix} = {{\frac{1}{\sqrt{4}}\begin{bmatrix}1 & 0 & j & 0 \\0 & 1 & 0 & j \\0 & {- 1} & 0 & j \\1 & 0 & {- j} & 0\end{bmatrix}}\begin{bmatrix}{{Re}\left( s_{1} \right)} \\{{Re}\left( s_{2} \right)} \\{{Im}\left( s_{1} \right)} \\{{Im}\left( s_{2} \right)}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 7} \right\rbrack\end{matrix}$

In Equation 7, s₁ denotes a 1^(st) symbol, s₂ denotes a 2^(nd) symbol,and s(k) denotes a k^(th) Tx symbol (where k=1, 2, 3, 4). A 1^(st) Txvector consists of s(1) and s(2), and a 2^(nd) Tx vector consists ofs(3) and s(4). 1/root(4) is a normalization factor.

Equation 7 can be rearranged to Equation 8 below.

$\begin{matrix}{\begin{bmatrix}{s(1)} \\{s(2)} \\{s(3)} \\{s(4)}\end{bmatrix} = {{\frac{1}{\sqrt{4}}\begin{bmatrix}{{{Re}\left( s_{1} \right)} + {j\; {{Im}\left( s_{1} \right)}}} \\{{{Re}\left( s_{2} \right)} + {j\; {{Im}\left( s_{2} \right)}}} \\{{- {{Re}\left( s_{2} \right)}} + {j\; {{Im}\left( s_{2} \right)}}} \\{{{Re}\left( s_{1} \right)} - {j\; {{Im}\left( s_{1} \right)}}}\end{bmatrix}} = {\frac{1}{\sqrt{4}}\begin{bmatrix}s_{1} \\s_{2} \\{- s_{2}^{*}} \\s_{1}^{*}\end{bmatrix}}}} & \left\lbrack {{Equation}\mspace{14mu} 8} \right\rbrack\end{matrix}$

For convenience of explanation, the normalization factor is omitted inthe following descriptions.

FIG. 19 is a flowchart showing an information transmission methodaccording to another embodiment of the present invention.

Referring to FIG. 19, a UE obtains a 1^(st) resource index and a 2^(nd)resource index (step S210). The UE generates 1^(st) and 2^(nd) symbolscorresponding to information (step S220). The UE generates 1^(st) and2^(nd) Tx vectors from the 1^(st) and 2^(nd) symbols on the basis of anAlamouti code (step S230). The UE transmits the 1^(st) Tx vector througha 1^(st) antenna, and transmits the 2^(nd) Tx vector through a 2^(nd)antenna (step S240). In this case, the 1^(st) Tx vector consists of1^(st) and 2^(nd) Tx symbols. The 1^(st) Tx symbol is transmitted basedon the 1^(st) resource index, and the 2^(nd) Tx symbol is transmittedbased on the 2^(nd) resource index. The 2^(nd) Tx vector consists of3^(rd) and 4^(th) Tx symbols. The 3^(rd) Tx symbol is transmitted basedon the 1^(st) resource index, and the 4^(th) Tx symbol is transmittedbased on the 2^(nd) resource index.

Hereinafter, a method of obtaining the 1^(st) resource index and the2^(nd) resource index will be described.

First, the UE may receive the 1^(st) resource index and the 2^(nd)resource index from a BS. For example, a plurality of resource indicesmay be directly signaled in such a manner that the 1^(st) resource indexis set to 0 and the 2^(nd) resource index is set to 2. Second, the UEmay implicitly know the 1^(st) resource index and the 2^(nd) resourceindex. The 1^(st) resource index may be obtained from a radio resourcefor a physical control channel for receiving 1^(st) DL data, and the2^(nd) resource index may be obtained from a radio resource for aphysical control channel for receiving 2^(nd) DL data. For example, the1^(st) resource index may be determined by using a 1^(st) CCE index usedfor PDCCH transmission on a 1^(st) DL carrier, and the 2^(nd) resourceindex may be determined by using a CCE index used for PDCCH transmissionon a 2^(nd) DL carrier. Third, the UE may receive the 1^(st) resourceindex from the BS and obtain the 2^(nd) resource index from the 1^(st)resource index. In this case, the 2^(nd) resource index is predeterminedaccording to the 1^(st) resource index. For example, if the 1^(st)resource index is 0, the 2^(nd) resource index may be predetermined to5, and if the 1^(st) resource index is 1, the 2^(nd) resource index maybe predetermined to 6. When the BS signals only a value 0 or 1 as the1^(st) resource index, the UE may obtain a value 5 or 6 as the 2^(nd)resource index from the 1^(st) resource index.

Hereinafter, a method of obtaining the 1^(st) resource index and the2^(nd) resource index by the UE will be described in case of dynamicACK/NACK transmission.

The UE may implicitly obtain the 1^(st) resource index from the 1^(st)CCE index used for PDCCH transmission with respect to PDSCH similarly to3GPP LTE(Release 8). The 2^(nd) resource index may be explicitlyreported by the BS. As a method of explicitly reporting the 2^(nd)resource index, signaling of a physical layer or signaling of a higherlayer (e.g., RRC) of the physical layer may be used. For the physicallayer signaling, the PDCCH may include an information field indicatingthe 2^(nd) resource index.

First, the UE may implicitly know the 1^(st) resource index from the1^(st) CCE index used for PDCCH transmission. Further, the UE may knowthe 2^(nd) resource index by using RRC signaling.

Second, the UE may know the 1^(st) resource index from the 1^(st) CCEindex used for PDCCH transmission. Further, the UE may know the 2^(nd)resource index by using an information field included in the PDCCH.

By using this method, signaling is prevented from being performed on allresource indices, thereby decreasing signaling overhead. In addition,the method allows coexistence with the legacy UE to which 3GPP LTE isapplied.

In case of single-antenna transmission, it is assumed that 18 UEs can bemultiplexed for one RB. In this case, if the SBC informationtransmission method is used for 2 Tx antennas, 9 UEs can be multiplexedfor one RB. In case of the PUCCH formats 1/1a/1b, the same controlinformation is transmitted in a 1^(st) slot and a 2^(nd) slot. An RBallocated to the PUCCH is hopped in a slot level. That is, since theinformation is transmitted using different subcarriers over time, afrequency diversity gain can be obtained. However, if the diversity gaincan be obtained sufficiently by using the SBC information transmissionmethod, it is not necessary to transmit the same information in the1^(st) slot and the 2^(nd) slot. Therefore, different information may betransmitted in the 1^(st) slot and the 2^(nd) slot. In this case, UEmultiplexing capacity of 2-antenna transmission may be maintained to bethe same as UE multiplexing capacity of single-antenna transmission. Forexample, if 18 UEs are multiplexed for one RB in case of single-antennatransmission, 18 UE can be multiplexed for one RB even in case of2-antenna transmission.

FIG. 20 is a flowchart showing an information transmission methodaccording to another embodiment of the present invention.

Referring to FIG. 20, a UE confirms a transmission mode (step S310). Thetransmission mode may indicate either single-antenna transmission ormultiple-antenna transmission. The UE transmits information according tothe transmission mode, and if the transmission mode indicates themultiple-antenna transmission, transmits the information by using theSBC information transmission method (step S320).

The transmission mode of the UE is adaptable according to a channelcondition or a traffic load condition. The transmission mode may besemi-statically determined. The transmission mode may be determined by ahigher layer such as an RRC layer. For example, a 1^(st) UE in a poorchannel environment may perform multiple-antenna transmission, and a2^(nd) UE in a good channel environment may perform single-antennatransmission. Alternatively, single-antenna transmission may beperformed if a great number of UEs are multiplexed to the same timeresource, and multiple-antenna transmission may be performed if arelatively small number of UEs are multiplexed. Therefore, the SBCinformation transmission method may also apply in an adaptive manneraccording to the transmission mode of the UE.

The SBC information transmission method can be extendedly applied tothree or more Tx antennas. As to the three or more Tx antennas, thismethod may be applied by combining with a different Tx diversity scheme.Examples of the different Tx diversity scheme include CDD, PVS,frequency switched transmit diversity (FSTD), time switched transmitdiversity (TSTD), etc. For example, when using 4 Tx antennas, theantennas are divided into a 1^(st) group including 2 Tx antennas and a2^(nd) group including 2 Tx antennas. The SBC information transmissionmethod may be applied to each group, and a different Tx diversity schememay be applied to each group.

Hereinafter, for convenience of explanation, a Tx matrix is describedfocusing on the example (1) of Table 14 when using 2 Tx antennas.

A Tx matrix similar to the example (1) of Table 14 is generated based onan Alamouti code from 1^(st) and 2^(nd) symbols s₁ and s₂ correspondingto information.

A 1^(st) receive (Rx) signal for a 1^(st) resource index is denoted byy₁, and a 2^(nd) Rx signal for a 2^(nd) resource index is denoted by y₂.An actual Rx signal y is received by combining the 1^(st) Rx signal y₁and the 2^(nd) Rx signal y₂ (y=y₁+y₂). However, it is assumed that theRx signal y can be split into the 1^(st) Rx signal y₁ and the 2^(nd) Rxsignal y₂ by using a de-spreading operation. For convenience ofexplanation, it is assumed that the number of Rx antennas of a receiveris one.

An Rx signal matrix can be expressed by Equation 9 below.

$\begin{matrix}{\begin{bmatrix}y_{1} \\y_{2}\end{bmatrix} = {{\begin{bmatrix}s_{1} & s_{2} \\{- s_{2}^{*}} & s_{1}^{*}\end{bmatrix}\begin{bmatrix}h_{1} \\h_{2}\end{bmatrix}} + \begin{bmatrix}n_{1} \\n_{2}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 9} \right\rbrack\end{matrix}$

In Equation 9, h₁ denotes a channel for a 1^(st) Tx antenna, h₂ denotesa channel for a 2^(nd) Tx antenna, n₁ denotes noise of a 1^(st) Rxsignal, and n₂ is noise of a 2^(nd) Rx signal. Herein, the noise may beadditive white Gaussian noise (AWGN).

Equation 9 can be equivalently expressed by Equation 10 below.

$\begin{matrix}{\begin{bmatrix}y_{1} \\y_{2}^{*}\end{bmatrix} = {{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}\begin{bmatrix}s_{1} \\s_{2}\end{bmatrix}} + \begin{bmatrix}n_{1} \\n_{2}^{*}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 10} \right\rbrack\end{matrix}$

Equation 10 can be modified to Equation 11 below.

$\begin{matrix}\begin{matrix}{{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}^{H}\begin{bmatrix}y_{1} \\y_{2}^{*}\end{bmatrix}} = {{{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}^{H}\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}}\begin{bmatrix}s_{1} \\s_{2}\end{bmatrix}} +}} \\{{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}^{H}\begin{bmatrix}n_{1} \\n_{2}^{*}\end{bmatrix}}} \\{= {{\begin{bmatrix}{{h_{1}}^{2} + {h_{2}}^{2}} & 0 \\0 & {{h_{1}}^{2} + {h_{2}}^{2}}\end{bmatrix}\begin{bmatrix}s_{1} \\s_{2}\end{bmatrix}} + \begin{bmatrix}n_{1}^{\prime} \\n_{2}^{\prime}\end{bmatrix}}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 11} \right\rbrack\end{matrix}$

In Equation 11, (•)^(H) denotes a Hermitian matrix. The 1^(st) symbol s₁and the 2^(nd) symbol s₂ are orthogonally separated. The receiver canobtain a diversity gain expressed by Equation 12 below.

|h ₁|² +|h ₂|²  [Equation 12]

The diversity gain is similar to maximal ratio coding (MRC) which isoptimal combining. The MRC scheme is one of signal combining schemes forestimating a Tx signal from an Rx signal received from a plurality of Rxantennas.

First, a case where each of 1^(st) and 2^(nd) symbols is onecomplex-valued symbol will be described according to 1^(st) to 4^(th)embodiments. The 1^(st) symbol is denoted by d₁(0), and the 2^(nd)symbol is denoted by d₂(0). A 1^(st) Tx vector includes a 1^(st) Txsymbol d₁(0) and a 2^(nd) Tx symbol −d₂(0)*, and the 2^(nd) Tx vectorincludes a 3^(rd) Tx symbol d₂(0) and a 4^(th) Tx symbol d₁(0)*.

In the 1^(st) and 2^(nd) embodiments, a resource used for informationtransmission consists of only a sequence. In this case, a resource indexincludes a sequence index indicating the sequence. The sequence may be afrequency-domain sequence or a time-domain sequence. A 1^(st) resourceindex and a 2^(nd) resource index include different sequence indices.

An m^(th) sequence having a spreading factor K=N indicated by an m^(th)resource index is denoted by [w_(m)(0), w_(m)(1), w_(m)(N−1)] (where Nis a natural number, m=1,2). An r^(th) Tx sequence is denoted by[z_(r)(0), z_(r)(1), . . . , z_(r)(N−1)] (where r=1, 2, 3, 4). A 1^(st)Tx sequence z₁ to a 4^(th) Tx sequence z₄ can be expressed by Equation13 below.

z ₁(k)=d ₁(0)·w ₁(k)

z ₂(k)=−d ₂(0)*·w ₂(k)

z ₃(k)=d ₂(0)·w ₁(k)

z ₄(k)=d ₁(0)*·w ₂(k)  [Equation 13]

In Equation 13, k=0, 1, 2, . . . , N−1.

If a sequence indicated by a sequence index included in a resource indexis a frequency-domain sequence, a Tx sequence is mapped to a frequencydomain. If the sequence is a time-domain sequence, the Tx sequence ismapped to a time domain.

Therefore, an r^(th) Tx sequence may be mapped either to the time domainor the frequency domain. When it is mapped to the frequency domain, ther^(th) spread sequence may be mapped to N subcarriers. When it is mappedto the time domain, the r^(th) spread sequence may be mapped to N timesamples, N chips, or N OFDM symbols.

A 1^(st) Tx sequence and a 2^(nd) Tx sequence are transmitted through a1^(st) antenna. A 3^(rd) Tx sequence and a 4^(th) Tx sequence aretransmitted through a 2^(nd) antenna.

1. 1^(st) Embodiment

The 1^(s) embodiment shows a case where a Walsh-Hadamard matrix is usedas a sequence.

Equation 14 below shows a 4×4 Walsh-Hadamard matrix.

$\begin{matrix}\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\1 & 1 & {- 1} & {- 1} \\1 & {- 1} & {- 1} & 1\end{bmatrix} & \left\lbrack {{Equation}\mspace{14mu} 14} \right\rbrack\end{matrix}$

Each of four rows of the Walsh-Hadamard matrix constitutes an orthogonalsequence. That is, four orthogonal sequences [1, 1, 1, 1], [1, −1, 1,−1], [1, 1, −1, −1], and [1, −1, −1, 1] can be defined. Although threeorthogonal sequences are used by excluding [1, 1, −1, −1] in 3GPP LTE(see Table 3), it is also possible to use [1, 1, −1, −1] as thesequence.

In an example described hereinafter, a 1^(st) orthogonal sequenceindicated by the 1^(st) resource index is [1, 1, 1, 1], and a 2^(nd)orthogonal sequence indicated by the 2^(nd) resource index is [1, −1, 1,−1].

The 1^(st) Tx sequence transmitted through the 1^(st) antenna is [d₀(0),−d₁(0), d₁(0), −d₁(0)], and the 2^(nd) Tx sequence is [−d₂(0)*, −d₂(0)*,d₂(0)*, d₂(0)*]. The 3^(rd) Tx sequence transmitted through the 2^(nd)antenna is [d₂(0), −d₂(0), d₂(0), −d₂(0)], and the 4^(th) Tx sequence is[d₁(0)*, d₁(0)*, −d₁(0)*, −d₁(0)*]. When Rx signals are denoted byy=[y(0), y(1), y(2), y(3)], each Rx signal can be expressed by Equation15 below.

y(0)={d ₁(0)−d ₂(0)*}h ₁ +{d ₂(0)+d ₁(0)*}h ₂ +n(0)

y(1)={−d ₁(0)−d ₂(0)*}h ₁ +{−d ₂(0)+d ₁(0)*}h ₂ +n(1)

y(2)={d ₁(0)+d ₂(0)*}h ₁ +{d ₂(0)−d ₁(0)*}h ₂ +n(2)

y(3)={−d ₁(0)+d ₂(0)*}h ₁ +{−d ₂(0)−d ₁(0)*}h ₂ +n(3)  [Equation 15]

Two estimation symbols can be generated by performing de-spreading oneach of two resource indices from the Rx signal. When d′_(m)(0) denotesan m^(th) estimation symbol which is de-spread with respect to an m^(th)resource index, it can be expressed by Equation 16 below ((m=1,2).

$\begin{matrix}{{d_{m}^{\prime}(0)} = {\sum\limits_{k = 0}^{N - 1}\; {{y(k)} \cdot \left( {w_{m}(k)} \right)^{*}}}} & \left\lbrack {{Equation}\mspace{14mu} 16} \right\rbrack\end{matrix}$

In Equation 16, N denotes a sequence length, and w_(m)(k) denotes ak^(th) element of an m^(th) sequence.

When d′₁(0) denotes a 1^(st) estimation symbol which is de-spread byusing a 1^(st) sequence from the Rx signal and d′₂(0) denotes a 2^(nd)estimation symbol which is de-spread by using a 2^(nd) sequence from theRx signal, they can be expressed by Equation 17 below.

$\begin{matrix}\begin{matrix}{{d_{1}^{\prime}(0)} = {{y(0)} - {y(1)} + {y(2)} - {y(3)}}} \\{= {\left\lbrack {{\left\{ {{d_{1}(0)} - {d_{2}(0)}^{*}} \right\} h_{1}} + {\left\{ {{d_{2}(0)} + {d_{1}(0)}^{*}} \right\} h_{2}} + {n(0)}} \right\rbrack -}} \\{{\left\lbrack {{\left\{ {{- {d_{1}(0)}} - {d_{2}(0)}^{*}} \right\} h_{1}} + {\left\{ {{- {d_{2}(0)}} + {d_{1}(0)}^{*}} \right\} h_{2}} + {n(1)}} \right\rbrack +}} \\{{\left\lbrack {{\left\{ {{d_{1}(0)} + {d_{2}(0)}^{*}} \right\} h_{1}} + {\left\{ {{d_{2}(0)} - {d_{1}(0)}^{*}} \right\} h_{2}} + {n(2)}} \right\rbrack -}} \\{\left\lbrack {{\left\{ {{- {d_{1}(0)}} + {d_{2}(0)}^{*}} \right\} h_{1}} + {\left\{ {{- {d_{2}(0)}} - {d_{1}(0)}^{*}} \right\} h_{2}} + {n(3)}} \right\rbrack} \\{= {{4{d_{1}(0)}h_{1}} + {4{d_{2}(0)}h_{2}} + n_{1}}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 17} \right\rbrack \\\begin{matrix}{{d_{2}^{\prime}(0)} = {{y(0)} + {y(1)} - {y(2)} - {y(3)}}} \\{= {\left\lbrack {{\left\{ {{d_{1}(0)} - {d_{2}(0)}^{*}} \right\} h_{1}} + {\left\{ {{d_{2}(0)} + {d_{1}(0)}^{*}} \right\} h_{2}} + {n(0)}} \right\rbrack +}} \\{{\left\lbrack {{\left\{ {{- {d_{1}(0)}} - {d_{2}(0)}^{*}} \right\} h_{1}} + {\left\{ {{- {d_{2}(0)}} + {d_{1}(0)}^{*}} \right\} h_{2}} + {n(1)}} \right\rbrack -}} \\{{\left\lbrack {{\left\{ {{d_{1}(0)} + {d_{2}(0)}^{*}} \right\} h_{1}} + {\left\{ {{d_{2}(0)} - {d_{1}(0)}^{*}} \right\} h_{2}} + {n(2)}} \right\rbrack -}} \\{\left\lbrack {{\left\{ {{- {d_{1}(0)}} + {d_{2}(0)}^{*}} \right\} h_{1}} + {\left\{ {{- {d_{2}(0)}} - {d_{1}(0)}^{*}} \right\} h_{2}} + {n(3)}} \right\rbrack} \\{= {{{- 4}{d_{2}(0)}^{*}h_{1}} + {4{d_{1}(0)}^{*}h_{2}} + n_{2}}}\end{matrix} & \;\end{matrix}$

Equation 17 can be expressed by a matrix of Equation 18 below.

$\begin{matrix}{\begin{bmatrix}{d_{1}^{\prime}(0)} \\{d_{2}^{\prime}(0)}\end{bmatrix} = {{{4\begin{bmatrix}{d_{1}(0)} & {d_{2}(0)} \\{- {d_{2}(0)}^{*}} & {d_{1}(0)}^{*}\end{bmatrix}}\begin{bmatrix}h_{1} \\h_{2}\end{bmatrix}} + \begin{bmatrix}n_{1} \\n_{2}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 18} \right\rbrack\end{matrix}$

Equation 18 can be modified to Equation 19 below.

$\begin{matrix}{\begin{bmatrix}{d_{1}^{\prime}(0)} \\{d_{2}^{\prime}(0)}^{*}\end{bmatrix} = {{{4\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}}\begin{bmatrix}{d_{2}(0)} \\{d_{1}(0)}\end{bmatrix}} + \begin{bmatrix}n_{1} \\n_{2}^{*}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 19} \right\rbrack\end{matrix}$

A 1^(st) symbol d₁(0) and a 2^(nd) symbol d₂(0) can be detected by usingEquation 20 below.

$\begin{matrix}{{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}^{H}\begin{bmatrix}{d_{1}^{\prime}(0)} \\{d_{2}^{\prime}(0)}^{*}\end{bmatrix}} = {{{4\begin{bmatrix}{{h_{1}}^{2} + {h_{2}}^{2}} & 0 \\0 & {{h_{1}}^{2} + {h_{2}}^{2}}\end{bmatrix}}\begin{bmatrix}{d_{1}(0)} \\{d_{2}(0)}\end{bmatrix}} + \begin{bmatrix}n_{1}^{''} \\n_{2}^{''}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 20} \right\rbrack\end{matrix}$

In this manner, the diversity gain is obtained.

2. 2^(nd) Embodiment

The 1^(st) embodiment is a case where a discrete Fourier transform (DFT)code is used as a sequence. The use of the DFT code is equivalent to acyclic shift in a different domain. That is, the use of the DFT code ina time domain is equivalent to a cyclic shift in a frequency domain. Inaddition, the use of the DFT code in the frequency domain is equivalentto a cyclic shift in the time domain.

Equation 21 below shows a 4×4 DFT code matrix.

$\begin{matrix}\begin{bmatrix}1 & ^{{j2\pi} \cdot 1 \cdot {0/4}} & ^{{j2\pi} \cdot 2 \cdot {0/4}} & ^{{j2\pi} \cdot 3 \cdot {0/4}} \\1 & ^{{j2\pi} \cdot 1 \cdot {1/4}} & ^{{j2\pi} \cdot 2 \cdot {1/4}} & ^{{j2\pi} \cdot 3 \cdot {1/4}} \\1 & ^{{j2\pi} \cdot 1 \cdot {2/4}} & ^{{j2\pi} \cdot 2 \cdot {2/4}} & ^{{j2\pi} \cdot 3 \cdot {2/4}} \\1 & ^{{j2\pi} \cdot 1 \cdot {3/4}} & ^{{j2\pi} \cdot 2 \cdot {3/4}} & ^{{j2\pi} \cdot 3 \cdot {3/4}}\end{bmatrix} & \left\lbrack {{Equation}\mspace{14mu} 21} \right\rbrack\end{matrix}$

Each of four rows of the DFT code matrix constitutes an orthogonalsequence. That is, 4 sequences having a length of 4 can be defined fromthe DFT code matrix.

Hereinafter, a case where a 1^(st) sequence w₁ and a 2^(nd) sequence w₂are defined by Equation 22 will be described for example.

w ₁=[1,e ^(j2π·1·1/4) ,e ^(j2π·2·1/4) ,e ^(j2π·3·1/4])

w ₂=[1,e ^(j2π·1·2/4) ,e ^(j2π·2·2/4) ,e ^(j2π·3·2/4])  Equation 221

A 1^(st) Tx sequence z₁ to a 4^(th) Tx sequence z₄ can be expressed byEquation 23 below.

z ₁ =[d ₁(0),d ₁(0)e ^(j2π·1·1/4) ,d ₁(0)e ^(j2π·2·1/4) ,d ₁(0)e^(j2π·3·1/4)]

z ₂ =[−d ₂(0)*,−d ₂(0)*e ^(j2π·1·2/4) ,−d ₂(0)*e ^(j2π·2·2/4) ,−d ₂(0)*e^(j2π·3·2/4)]

z ₃ =[d ₂(0),d ₂(0)e ^(j2π·1·1/4) ,d ₂(0)e ^(j2π·2·1/4) ,d ₂(0)e^(j2π·3·1/4)]

z ₄ =[d ₁(0)*,d ₁(0)*e ^(j2π·1·2/4) ,d ₁(0)*e ^(j2π·2·2/4) ,d ₁(0)*e^(j2π·3·2/4)]  [Equation 23]

When d′₁(0) denotes a 1^(st) estimation symbol which is de-spread withrespect to the 1^(st) sequence w₁ and d′₂(0) denotes a 2^(nd) estimationsymbol which is de-spread with respect to the 2^(nd) sequence w₂, theycan be expressed by Equation 24 below.

d′ ₁(0)=4d ₁(0)h ₁+4d ₂(0)h ₂ +n ₁

d′ ₂(0)=−4d ₂(0)*h ₁+4d ₁(0)*h ₂ +h ₂ +n ₂  [Equation 24]

By using Equation 24, a 1^(st) symbol d₁(0) and a 2^(nd) symbol d₂(0)can be detected by Equation 25 below.

$\begin{matrix}{{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}^{H}\begin{bmatrix}{d_{1}^{\prime}(0)} \\{d_{2}^{\prime}(0)}^{*}\end{bmatrix}} = {{{4\begin{bmatrix}{{h_{1}}^{2} + {h_{2}}^{2}} & 0 \\0 & {{h_{1}}^{2} + {h_{2}}^{2}}\end{bmatrix}}\begin{bmatrix}{d_{1}(0)} \\{d_{2}(0)}\end{bmatrix}} + \begin{bmatrix}n_{1}^{\prime} \\n_{2}^{\prime}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 25} \right\rbrack\end{matrix}$

In this manner, the diversity gain is obtained.

3. 3^(rd) Embodiment

The 3^(rd) embodiment is a case where a resource used for informationtransmission consists of a time-domain sequence and a frequency-domainsequence. In this case, a resource index includes a time-domain sequenceindex and a frequency-domain sequence index. The time-domain sequenceand the frequency-domain sequence allow a Tx symbol to be spread to a 2dimensional (2D) domain, i.e., a time-frequency domain. It is assumed inthe 3^(rd) embodiment that the time-domain sequence is one orthogonalsequence selected from a set of orthogonal sequences, and thefrequency-domain sequence is a cyclically shifted sequence generated bycyclically shifting a base sequence by a cyclic shift (CS) amount.However, this is for exemplary purposes only, and thus the time-domainsequence and/or the frequency-domain sequence are not limited thereto.The time-domain sequence index may be an orthogonal sequence (OS) index,and the frequency-domain sequence may be a CS index indicating the CSamount.

A 1^(st) resource index and a 2^(nd) resource index include a differentfrequency-domain sequence index or a different time-domain sequence.

An r^(th) Tx sequence z_(r) (r=1, 2, 3, 4) can be expressed in the 2Ddomain, i.e., the time-frequency domain, by Equation 26 below.

$\begin{matrix}\begin{bmatrix}{z_{r}\left( {0,0} \right)} & {z_{r}\left( {0,1} \right)} & {z_{r}\left( {0,2} \right)} & {z_{r}\left( {0,3} \right)} \\{z_{r}\left( {1,0} \right)} & {z_{r}\left( {1,1} \right)} & {z_{r}\left( {1,2} \right)} & {z_{r}\left( {1,3} \right)} \\\vdots & \vdots & \vdots & \vdots \\{z_{r}\left( {11,0} \right)} & {z_{r}\left( {11,1} \right)} & {z_{r}\left( {11,2} \right)} & {z_{r}\left( {11,3} \right)}\end{bmatrix} & \left\lbrack {{Equation}\mspace{14mu} 26} \right\rbrack\end{matrix}$

Herein, each row may correspond to a subcarrier, and each column maycorrespond to an OFDM symbol. Each element of the matrix may be mappedto a resource element of an RB used in information transmission.Although the matrix consists of 12 rows and 4 columns herein, this isfor exemplary purposes only, and thus the number of rows and the numberof columns of the matrix are not limited thereto.

The 1^(st) Tx sequence z₁ to the 4^(th) Tx sequence z₄ can be expressedby Equation 27 below.

z ₁(n,k)=w ₁(k)d ₁(0)r(n,Ics ¹)

z ₂(n,k)=w ₂(k)(−d ₂(0)*)r(n,Ics ²)

z ₃(n,k)=w ₁(k)d ₂(0)r(n,Ics ¹)

z ₄(n,k)=w ₂(k)d ₁(0)*r(n,Ics ²)  [Equation 27]

In Equation 27, k denotes a symbol index of an OFDM symbol. Except foran OFDM symbol on which an RS is carried, k may be set to k=0, 1, 2, 3.n denotes a subcarrier index (n=0, 1, . . . , 11). w_(m)(k) denotes ak^(th) element of an m^(th) OS index, Ics^(m) denotes an m^(th) CSindex, and r(n,Ics^(m)) denotes an m^(th) cyclically shifted sequence(m=1,2).

The 3^(rd) embodiment can consider three cases, i.e., (1) a case where1^(st) and 2^(nd) frequency-domain sequence indices are different fromeach other and 1^(st) and 2^(nd) time-domain sequence indices areidentical to each other, (2) a case where the 1^(st) and 2^(nd)frequency-domain sequence indices are different from each other and the1^(st) and 2^(nd) time-domain sequence indices are different from other,and (3) a case where the 1^(st) and 2^(nd) frequency-domain sequenceindices are identical to each other and the 1^(st) and 2^(nd)time-domain sequence indices are different from each other. Each of thethree cases will be described below.

(1) The case where the 1^(st) and 2^(nd) frequency-domain sequenceindices are different from each other and the 1^(st) and 2^(nd)time-domain sequence indices are identical to each other.

For example, it is assumed that the 1^(st) resource index indicates 0 asthe 1^(st) frequency-domain sequence index, and indicates [1, 1, 1, 1]as the 1^(st) time-domain sequence. In addition, it is assumed that the2^(nd) resource index indicates 2 as the 2^(nd) frequency-domainsequence, and indicates [1, 1, 1, 1] as the 2^(nd) time-domain sequence.

The 1^(st) Tx sequence z₁ to the 4^(th) Tx sequence z₄ can be expressedby Equation 28 below.

$\begin{matrix}{{{z_{1}\left( {n,k} \right)} = {{w_{1}(k)} \cdot {d_{1}(0)} \cdot {r(n)} \cdot {\exp \left( \frac{{j2\pi} \cdot 0 \cdot n}{12} \right)}}}{{z_{2}\left( {n,k} \right)} = {{w_{2}(k)} \cdot \left( {- {d_{2}(0)}^{*}} \right) \cdot {r(n)} \cdot {\exp \left( \frac{{j2\pi} \cdot 2 \cdot n}{12} \right)}}}{{z_{3}\left( {n,k} \right)} = {{w_{1}(k)} \cdot {d_{2}(0)} \cdot {r(n)} \cdot {\exp \left( \frac{{j2\pi} \cdot 0 \cdot n}{12} \right)}}}{{z_{4}\left( {n,k} \right)} = {{w_{2}(k)} \cdot {d_{1}(0)}^{*} \cdot {r(n)} \cdot {\exp \left( \frac{{j2\pi} \cdot 2 \cdot n}{12} \right)}}}} & \left\lbrack {{Equation}\mspace{14mu} 28} \right\rbrack\end{matrix}$

In Equation 28, r(n) is a base sequence.

An Rx signal y(n,k) can be expressed by Equation 29 below (where 0≦n≦11,0≦k≦3, n and k are integers).

y(n,k)=(z ₁(n,k)+z ₂(n,k)h ₁+(z ₃(n,k)+z ₄(n,k))h ₂ +n(n,k)  [Equation29]

When d′₁(0) denotes a 1^(st) estimation symbol which is de-spread withrespect to the 1^(st) resource index from the Rx signal and d′₂(0)denotes a 2^(nd) estimation symbol which is de-spread with respect tothe 2^(nd) resource index from the Rx signal, they can be expressed byEquation 30 below.

d′ ₁(0)=48d ₁(0)h ₁+48d ₂(0)h ₂ +n ₁

d′ ₂(0)=−48d ₂(0)*h ₁+48d ₁(0)*h ₂ +n ₂  [Equation 30]

In Equation 30, if de-spreading is performed on a cyclic shift, a simplefrequency coherent detector can be used, or an IFFT-based maximumlikelihood (ML) detector can be used.

Equation 30 can be expressed by a matrix of Equation 31 below.

$\begin{matrix}{\begin{bmatrix}{d_{1}^{\prime}(0)} \\{d_{2}^{\prime}(0)}\end{bmatrix} = {{{48\begin{bmatrix}{d_{1}(0)} & {d_{2}(0)} \\{- {d_{2}(0)}^{*}} & {d_{1}(0)}^{*}\end{bmatrix}}\begin{bmatrix}h_{1} \\h_{2}\end{bmatrix}} + \begin{bmatrix}n_{1} \\n_{2}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 31} \right\rbrack\end{matrix}$

A 1^(st) symbol d₁(0) and a 2^(nd) symbol d₂(0) can be detected byEquation 32 below.

$\begin{matrix}{{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}^{H}\begin{bmatrix}{d_{1}^{\prime}(0)} \\{d_{2}^{\prime}(0)}^{*}\end{bmatrix}} = {\quad{{{48\begin{bmatrix}{{h_{1}}^{2} + {h_{2}}^{2}} & 0 \\0 & {{h_{1}}^{2} + {h_{2}}^{2}}\end{bmatrix}}\begin{bmatrix}{d_{1}(0)} \\{d_{2}(0)}\end{bmatrix}} + \begin{bmatrix}n_{1}^{\prime} \\n_{2}^{\prime}\end{bmatrix}}}} & \left\lbrack {{Equation}\mspace{14mu} 32} \right\rbrack\end{matrix}$

In this manner, the diversity gain is obtained.

(2) The case where the 1^(st) and 2^(nd) frequency-domain sequenceindices are different from each other and the 1^(st) and 2^(nd)time-domain sequence indices are different from other.

For example, it is assumed that the 1^(st) resource index indicates 0 asthe 1^(st) frequency-domain sequence index, and indicates [1, 1, 1, 1]as the 1^(st) time-domain sequence. In addition, it is assumed that the2^(nd) resource index indicates 2 as the 2^(nd) frequency-domainsequence, and indicates [1, −1, 1, −1] as the 2^(nd) time-domainsequence.

The same diversity gain as the case (1) where the 1^(st) and 2^(nd)frequency-domain sequence indices are different from each other and the1^(st) and 2^(nd) time-domain sequence indices are identical to eachother can also be obtained.

(3) The case where the 1^(st) and 2^(nd) frequency-domain sequenceindices are identical to each other and the 1^(st) and 2^(nd)time-domain sequence indices are different from each other.

For example, it is assumed that the 1^(st) resource index indicates 0 asthe 1^(st) frequency-domain sequence index, and indicates [1, 1, 1, 1]as the 1^(st) time-domain sequence. In addition, it is assumed that the2^(nd) resource index indicates 0 as the 2^(nd) frequency-domainsequence, and indicates [1, −1, 1, −1] as the 2^(nd) time-domainsequence.

The same diversity gain as the case (1) where the 1^(st) and 2^(nd)frequency-domain sequence indices are different from each other and the1^(st) and 2^(nd) time-domain sequence indices are identical to eachother can also be obtained.

4. 4^(th) Embodiment

The 4^(th) embodiment is a case where a resource used for informationtransmission consists of a time-domain sequence, a frequency-domainsequence, and an RB. In this case, a resource index includes atime-domain sequence index, a frequency-domain sequence index, and RBinformation. Similarly to the 3^(rd) embodiment, it is assumed in the4^(th) embodiment that the time-domain sequence is one orthogonalsequence selected from a set of orthogonal sequences, and thefrequency-domain sequence is a cyclically shifted sequence generated bycyclically shifting a base sequence by a CS amount. However, this is forexemplary purposes only, and thus the time-domain sequence and/or thefrequency-domain sequence are not limited thereto. The time-domainsequence index may be an OS index, and the frequency-domain sequence maybe a CS index indicating the CS amount.

A 1^(st) resource index and a 2^(nd) resource index include a differentfrequency-domain sequence index or a different time-domain sequence.

A 1^(st) Tx sequence z₁ to a 4^(th) Tx sequence z₄ can be expressed byEquation 33 below.

z ₁(n+R ₁ ,k)=w ₁(k)d ₁(0)r(n,Ics ¹)

z ₂(n+R ₂ ,k)=w ₂(k)(−d ₂(0)*)r(n,Ics ²)

z ₃(n+R ₁ ,k)=w ₁(k)d ₂(0)r(n,Ics ¹)

z ₄(n+R ₂ ,k)=w ₂(k)d ₁(0)*r(n,Ics ²)  [Equation 33]

In Equation 33, k denotes a symbol index of an OFDM symbol in an m^(th)RB. Except for an OFDM symbol on which an RS is carried, k may be set tok=0, 1, 2, 3. R_(m) denotes a frequency position offset of the m^(th)RB, and n denotes a subcarrier index in the m^(th) RB (where n=0, 1, . .. , 11). w_(m)(k) denotes a k^(th) element of an m^(th) OS index,Ics^(m) denotes an m^(th) CS index, and r(n,Ics^(m)) denotes an m^(th)cyclically shifted sequence (m=1,2).

The 1^(st) RB indicated by the 1^(st) resource index may be identical toor different from the 2^(nd) RB indicated by the 2^(nd) RB. Even if the1^(st) RB and the 2^(nd) RB are identical to each other, orthogonalitycan be maintained when a 1^(st) CS index and a 2^(nd) CS index aredifferent from each other. In addition, even if the 1^(st) RB and the2^(nd) RB are identical to each other, orthogonality can be maintainedwhen a 1^(st) OS index and a 2^(nd) OS index are different from eachother. Therefore, the 4^(th) embodiment can consider two cases, i.e.,(1) a case where the 1^(st) RB and the 2^(nd) RB are identical to eachother, and (2) a case where the 1^(st) RB and the 2^(nd) RB aredifferent from each other. Each of the two cases will be describedbelow.

(1) The case where the 1^(st) RB and the 2^(nd) RB are identical to eachother.

R₁ and R₂ are identical to each other (R₁=R₂=R). An Rx signal y(n+R,k)can be expressed by Equation 34 below (where 0≦n≦11, 0≦k≦3, n and k areintegers).

y(n+R,k)=(z ₁(n+R,k)+z ₂(n+R,k))h ₁+(z ₃(n+R,k)+z ₄(n+R,k))h ₂ +n₀  [Equation 34]

When d′₁(0) denotes a 1^(st) estimation symbol which is de-spread withrespect to the 1^(st) resource index from the Rx signal and d′₂(0)denotes a 2^(nd) estimation symbol which is de-spread with respect tothe 2^(nd) resource index from the Rx signal, they can be expressed byEquation 35 below.

$\begin{matrix}{{d_{1}^{\prime}(0)} = {\sum\limits_{k = 0}^{3}{\sum\limits_{n = 0}^{11}\left( {{{{y\left( {{n + R},n} \right)} \cdot \left( {{w_{1}(k)}{r\left( {n,{Ics}^{1}} \right)}} \right)}{d_{2}^{\prime}(0)}} = {\sum\limits_{k = 0}^{3}{\sum\limits_{n = 0}^{11}\left( {{y\left( {{n + R},n} \right)} \cdot \left( {{w_{2}(k)}{r\left( {n,{Ics}^{2}} \right)}} \right)} \right.}}} \right.}}} & \left\lbrack {{Equation}\mspace{14mu} 35} \right\rbrack\end{matrix}$

For convenience of explanation, de-spreading based on simple summationis assumed herein. However, the de-spreading may be performed on anorthogonal sequence after detecting a cyclic shift by using theIFFT-based ML.

Equation 35 can be expressed by a matrix of Equation 36 below.

$\begin{matrix}{\begin{bmatrix}{d_{1}^{\prime}(0)} \\{d_{2}^{\prime}(0)}\end{bmatrix} = {{{48\begin{bmatrix}{d_{1}(0)} & {d_{2}(0)} \\{- {d_{2}(0)}^{*}} & {d_{1}(0)}^{*}\end{bmatrix}}\begin{bmatrix}h_{1} \\h_{2}\end{bmatrix}} + \begin{bmatrix}n_{1} \\n_{2}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 36} \right\rbrack\end{matrix}$

A 1^(st) symbol d₁(0) and a 2^(nd) symbol d₂(0) can be detected byEquation 37 below.

$\begin{matrix}{{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}^{H}\begin{bmatrix}{d_{1}^{\prime}(0)} \\{d_{2}^{\prime}(0)}^{*}\end{bmatrix}} = {{{48\begin{bmatrix}{{h_{1}}^{2} + {h_{2}}^{2}} & 0 \\0 & {{h_{1}}^{2} + {h_{2}}^{2}}\end{bmatrix}}\begin{bmatrix}{d_{1}(0)} \\{d_{2}(0)}\end{bmatrix}} + \begin{bmatrix}n_{1}^{\prime} \\n_{2}^{\prime}\end{bmatrix}}} & \left\lbrack {{Equation}\mspace{14mu} 37} \right\rbrack\end{matrix}$

In this manner, the diversity gain is obtained.

(2) The case where the 1^(st) RB and the 2^(nd) RB are different fromeach other.

R₁ and R₂ are different from each other. Rx signals y(n+R₁,k) andy(n+R₂,k) can be expressed by Equation 38 below (where 0≦n≦11, 0≦k≦3, nand k are integers).

y(n+R ₁ ,k)=z ₁(n+R ₁ ,k)h ₁ z ₃(n+R ₁ ,k)h ₂ +n ₁

y(n+R ₂ ,k)=z ₂(n+R ₂ ,k)h ₁ z ₄(n+R ₂ ,k)h ₂ +n ₂  [Equation 38]

When d′₁(0) denotes a 1^(st) estimation symbol which is de-spread withrespect to the 1^(st) resource index from the Rx signal and d′₂(0)denotes a 2^(nd) estimation symbol which is de-spread with respect tothe 2^(nd) resource index from the Rx signal, they can be expressed byEquation 39 below.

$\begin{matrix}{{d_{1}^{\prime}(0)} = {\sum\limits_{k = 0}^{3}{\sum\limits_{n = 0}^{11}\left( {{{{y\left( {{n + R_{1}},n} \right)} \cdot \left( {{w_{1}(k)}{r\left( {n,{Ics}^{1}} \right)}} \right)}{d_{2}^{\prime}(0)}} = {\sum\limits_{k = 0}^{3}{\sum\limits_{n = 0}^{11}\left( {{y\left( {{n + R_{2}},n} \right)} \cdot \left( {{w_{2}(k)}{r\left( {n,{Ics}^{2}} \right)}} \right)} \right.}}} \right.}}} & \left\lbrack {{Equation}\mspace{14mu} 39} \right\rbrack\end{matrix}$

The same diversity gain as the case (1) where the 1^(st) RB and the2^(nd) RB are identical to each other can also be obtained.

As such, the 1^(st) resource index may indicate the 1^(st)frequency-domain sequence index, the 1^(st) time-domain sequence index,and the 1^(st) RB, and the 2^(nd) resource index may indicate the 2^(nd)frequency-domain sequence index, the 2^(nd) time-domain sequence index,and the 2^(nd) RB. In the 1^(st) resource index and the 2^(nd) resourceindex, at least one of the RB information, the frequency-domain sequenceindex, and the time-domain sequence index is different. To decrease aCM, a scheduler of a BS may restrict the resource index to a case whereonly one of the frequency-domain sequence shift index, the time-domainsequence index, and the RB is different, for example: (1) a case wherethe 1^(st) and 2^(nd) time-domain sequence indices are identical to eachother, the 1^(st) and 2^(nd) RBs are identical to each other, and the1^(st) and 2^(nd) frequency-domain sequence indices are different fromeach other; (2) a case where the 1^(st) and 2^(nd) frequency-domainsequence indices are identical to each other, the 1^(st) and 2^(nd) RBsare identical to each other, and the 1^(st) and 2^(nd) time-domainsequence indices are different from each other; (3) a case where the1^(st) and 2^(nd) frequency-domain sequence indices are identical toeach other, the 1^(st) and 2^(nd) time-domain sequence indices areidentical to each other, and the 1^(st) and 2^(nd) RBs are differentfrom each other; (4) one of the cases (1) and (2); (5) one of the cases(1) and (3); (6) one of the cases (2) and (3); and (7) one of the cases(1), (2), and (3).

Now, a case where each of the 1^(st) symbol and the 2^(nd) symbolconsists of a plurality of complex-valued symbols will be described. Forexample, the 1^(st) symbol s₁ may be denoted by d₁(0), . . . , d₁(10),and the 2^(nd) symbol s₂ may be denoted by d₂(0), . . . , d₂(10).

5. 5^(th) Embodiment

A resource used for information transmission may consist of a sequenceand an RB. In this case, each resource index indicates a sequence indexand an RB. It is assumed herein that the sequence is a frequency-domainsequence, and is a cyclically shifted sequence generated by cyclicallyshifting a base sequence by a CS amount. However, this is for exemplarypurposes only, and thus the sequence is not limited thereto. Thesequence index may be a CS index indicating the CS amount.

A 1^(st) resource index and a 2^(nd) resource index include differentsequence indices or different RB information.

The UE determines an m^(th) CS index and an m^(th) RB by using an m^(th)resource index (where m=1,2). An element of an r^(th) spread sequencecan be expressed by Equation 40 below (where r=1, 2, 3, 4).

$\begin{matrix}{{{z_{1}\left( {{n + R_{1}},k} \right)} = {{d_{1}(k)} \cdot {r(n)} \cdot {\exp\left( \frac{{j2\pi}\; {nIcs}^{1}}{12} \right)}}}{{z_{2}\left( {{n + R_{2}},k} \right)} = {\left( {- {d_{2}(k)}^{*}} \right) \cdot {r(n)} \cdot {\exp\left( \frac{{j2\pi}\; {nIcs}^{2}}{12} \right)}}}{{z_{3}\left( {{n + R_{1}},k} \right)} = {{d_{2}(k)} \cdot {r(n)} \cdot {\exp\left( \frac{{j2\pi}\; {nIcs}^{1}}{12} \right)}}}{{z_{4}\left( {{n + R_{2}},k} \right)} = {{d_{1}(k)}^{*} \cdot {r(n)} \cdot {\exp\left( \frac{{j2\pi}\; {nIcs}^{2}}{12} \right)}}}} & \left\lbrack {{Equation}\mspace{14mu} 40} \right\rbrack\end{matrix}$

In Equation 40, k may be a symbol index of an OFDM symbol in an m^(th)RB. Except for OFDM symbols on which an RS is carried, k may be set tok=0, 1, . . . , 9. R_(m) denotes a frequency location offset of them^(th) RB, and n denotes a subcarrier index in the m^(th) RB (where n=0,1, . . . , 11). Ics^(m) denotes an m^(th) CS index, and r(n,Ics^(m))denotes an m^(th) cyclically shifted sequence.

As such, the 1^(st) resource index may indicate the 1^(st) sequenceindex and the 1^(st) RB, and the 2^(nd) resource index may indicate the2^(nd) sequence index and the 2^(nd) RB. In the 1^(st) resource indexand the 2^(nd) resource index, at least one of RB information and thesequence index is different. To decrease the CM, the scheduler of the BSmay restrict a resource index to: (1) a case where the 1^(st) and 2^(nd)sequence indices are different from each other and the 1^(st) and 2^(nd)RBs are identical to each other; (2) the 1^(st) and 2^(nd) sequenceindices are identical to each other and the 1^(st) and 2^(nd) RBs aredifferent from each other; and (3) one of the cases (1) and (2).

FIG. 21 shows an example of an information transmission method when a1^(st) RB and a 2^(nd) RB are identical to each other.

Referring to FIG. 21, the 1^(st) RB and the 2^(nd) RB are RB pairs withm=3. A 1^(st) Tx vector (i.e., a 1^(st) Tx symbol s₁ and a 2^(nd) Txsymbol −s₂*) is transmitted through a 1^(st) antenna. A 2^(nd) Tx vector(i.e., a 3^(rd) Tx symbol s₂ and a 4^(th) Tx symbol s₁*) is transmittedthrough a 2^(nd) antenna.

FIG. 22 shows an example of an information transmission method when a1^(st) RB and a 2^(nd) RB are different from each other.

Referring to FIG. 22, the 1^(st) RB is an RB pair with m=3, and the2^(nd) RB is an RB pair with m=0.

FIG. 23 is a block diagram showing an apparatus for radio communication.An apparatus 50 for radio communication may be a part of a UE. Theapparatus 50 includes a processor 51, a memory 52, a radio frequency(RF) unit 53, a display unit 54, and a user interface unit 55. The RFunit 53 is coupled to the processor 51 and transmits and/or receivesradio signals. The memory 52 is coupled to the processor 51 and storesan operating system, an application, and a general file. The displayunit 54 displays a variety of information of a UE and may use awell-known element such as a liquid crystal display (LCD), an organiclight emitting diode (OLED), etc. The user interface unit 55 can beconfigured with a combination of well-known user interfaces such as akeypad, a touch screen, etc. The block diagram of the transmitter ofFIG. 18 can be implemented by the processor 51.

FIG. 24 is a block diagram showing an example of a BS. A BS 60 includesa processor 61, a memory 62, a scheduler 63, and an RF unit 64. The RFunit 64 is coupled to the processor 61 and transmits and/or receivesradio signals. The processor 61 performs all methods related to theaforementioned information processing and transmission. The memory 62 iscoupled to the processor 61, and stores information processed in theprocessor 61. The scheduler 63 is coupled to the processor 61, and canperform all methods related to scheduling for information transmissionsuch as the aforementioned resource index allocation. The block diagramof the transmitter of FIG. 18 can be implemented by the processor 61.

As such, a method and apparatus for effective information transmissionin a radio communication system can be provided. A UE or a BS caneffectively transmit information by using a Tx diversity scheme.Orthogonality can be maintained between Tx antennas. A method ofeffectively transmitting information while maintaining compatibilitywith a single-carrier system can be provided in a multiple-carriersystem. In addition, additional control information can be effectivelytransmitted in a system supporting at least 2 codewords while satisfyingbackward compatibility with 3GPP LTE supporting up to 2 codewords.Accordingly, reliability of radio communication can be increased, andoverall system performance can be improved.

Although the above descriptions have focused on UL informationtransmission, the same can also apply to DL information transmissionwithout change. In addition, the aforementioned description can applynot only to control information transmission but also to generalinformation transmission such as data information transmission or thelike.

All functions described above may be performed by a processor such as amicroprocessor, a controller, a microcontroller, and an applicationspecific integrated circuit (ASIC) according to software or program codefor performing the functions. The program code may be designed,developed, and implemented on the basis of the descriptions of thepresent invention, and this is well known to those skilled in the art.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention as defined by the appended claims. The exemplary embodimentsshould be considered in descriptive sense only and not for purposes oflimitation. Therefore, the scope of the invention is defined not by thedetailed description of the invention but by the appended claims, andall differences within the scope will be construed as being included inthe present invention.

What is claimed is:
 1. A method of transmitting, by a transmitter, information in a wireless communication system, the method comprising: generating first and second symbols; generating first and second transmit vectors on the basis of an Alamouti code from the first and second symbols; and transmitting the first transmit vector through a first antenna and transmitting the second transmit vector through a second antenna, wherein the first transmit vector consists of a first transmit symbol and a second transmit symbol, and wherein the second transmit vector consists of a third transmit symbol and a fourth transmit symbol.
 2. The method of claim 1, wherein the first symbol is a first modulation symbol for first information, and the second symbol is a second modulation symbol for second information.
 3. The method of claim 1, wherein the first transmit symbol is generated based on the first symbol, the second transmit symbol is generated based on the second symbol, the third transmit symbol is obtained by appending a negative sign to a complex conjugate of the second transmit symbol, and the fourth transmit symbol is a complex conjugate of the first transmit symbol.
 4. The method of claim 1, wherein the resource index includes a sequence index indicating a sequence, and the sequence allows one of the transmit symbols to be spread to a frequency domain or a time domain, and wherein the first resource index and the second resource index include different sequence indices.
 5. The method of claim 4, wherein the sequence index indicates a cyclic shift amount, and the sequence is generated by cyclically shifting a base sequence by the cyclic shift amount.
 6. The method of claim 1, wherein the first transmit vector and the second transmit vector is transmitted through each frame including a control region and a data region having a plurality of OFDM symbols.
 7. A transmitter in a wireless communication system, the transmitter comprising: a modulator for generating a first symbol and a second symbol by modulating an information bit stream; a space block coding (SBC) processor for generating a first transmit vector consisting of a first transmit symbol and a second transmit symbol, and a second transmit symbol consisting of a third transmit symbol and a fourth transmit symbol on the basis of an Alamouti code from the first and second symbols; a first antenna for transmitting the first transmit vector; and a second antenna for transmitting the second transmit vector.
 8. The transmitter of claim 7, wherein the first symbol is a first modulation symbol for first information, and the second symbol is a second modulation symbol for second information.
 9. The transmitter of claim 7, wherein the first transmit symbol is generated based on the first symbol, the second transmit symbol is generated based on the second symbol, the third transmit symbol is obtained by appending a negative sign to a complex conjugate of the second transmit symbol, and the fourth transmit symbol is a complex conjugate of the first transmit symbol.
 10. The transmitter of claim 7, wherein the resource index includes a sequence index indicating a sequence, and the sequence allows a transmit symbol to be spread to a frequency domain or a time domain, and wherein the first resource index and the second resource index include different sequence indices.
 11. The transmitter of claim 10, wherein the sequence index indicates a cyclic shift amount, and the sequence is generated by cyclically shifting a base sequence by the cyclic shift amount.
 12. The transmitter of claim 7, wherein the first transmit vector and the second transmit vector is transmitted through each frame including a control region and a data region having a plurality of OFDM symbols. 